<?xml version="1.0" encoding="US-ASCII"?>
<!-- DFIN New ActiveDisclosure (SM) XBRL Linkbase Document - http://www.dfinsolutions.com/ -->
<!-- Creation Date :2023-03-06T15:36:31.8093+00:00 -->
<!-- Copyright (c) 2023 Donnelly Financial Solutions, Inc. All Rights Reserved. -->
<link:linkbase xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all" xlink:type="simple"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default" xlink:type="simple"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain" xlink:type="simple"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member" xlink:type="simple"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension" xlink:type="simple"/>
  <link:roleRef roleURI="http://www.seacormarine.com/20221231/taxonomy/role/Role_StatementConsolidatedStatementsOfComprehensiveIncomeLoss" xlink:href="smhi-20221231.xsd#Role_StatementConsolidatedStatementsOfComprehensiveIncomeLoss" xlink:type="simple"/>
  <link:roleRef roleURI="http://www.seacormarine.com/20221231/taxonomy/role/Role_StatementConsolidatedStatementsOfChangesInEquity" xlink:href="smhi-20221231.xsd#Role_StatementConsolidatedStatementsOfChangesInEquity" xlink:type="simple"/>
  <link:roleRef roleURI="http://www.seacormarine.com/20221231/taxonomy/role/Role_StatementConsolidatedStatementsOfChangesInEquityParenthetical" xlink:href="smhi-20221231.xsd#Role_StatementConsolidatedStatementsOfChangesInEquityParenthetical" xlink:type="simple"/>
  <link:roleRef roleURI="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureBusinessAcquisitionsTables" xlink:href="smhi-20221231.xsd#Role_DisclosureBusinessAcquisitionsTables" xlink:type="simple"/>
  <link:roleRef roleURI="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureNatureOfOperationsAndAccountingPoliciesAdditionalInformationDetails" xlink:href="smhi-20221231.xsd#Role_DisclosureNatureOfOperationsAndAccountingPoliciesAdditionalInformationDetails" xlink:type="simple"/>
  <link:roleRef roleURI="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureNatureOfOperationsAndAccountingPoliciesSummaryOfPropertyAndEquipmentFromContinuingOperationsDetails" xlink:href="smhi-20221231.xsd#Role_DisclosureNatureOfOperationsAndAccountingPoliciesSummaryOfPropertyAndEquipmentFromContinuingOperationsDetails" xlink:type="simple"/>
  <link:roleRef roleURI="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureNatureOfOperationsAndAccountingPoliciesSummaryOfPropertyAndEquipmentFromContinuingOperationsParentheticalDetails" xlink:href="smhi-20221231.xsd#Role_DisclosureNatureOfOperationsAndAccountingPoliciesSummaryOfPropertyAndEquipmentFromContinuingOperationsParentheticalDetails" xlink:type="simple"/>
  <link:roleRef roleURI="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureNatureOfOperationsAndAccountingPoliciesScheduleOfAccumulatedOtherComprehensiveLossIncomeDetails" xlink:href="smhi-20221231.xsd#Role_DisclosureNatureOfOperationsAndAccountingPoliciesScheduleOfAccumulatedOtherComprehensiveLossIncomeDetails" xlink:type="simple"/>
  <link:roleRef roleURI="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureTransformationFacilityRestructuringAndSeveranceChargesAdditionalInformationDetails" xlink:href="smhi-20221231.xsd#Role_DisclosureTransformationFacilityRestructuringAndSeveranceChargesAdditionalInformationDetails" xlink:type="simple"/>
  <link:roleRef roleURI="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureTransformationFacilityRestructuringAndSeveranceChargesScheduleOfComponentsOfRestructuringChargesDetails" xlink:href="smhi-20221231.xsd#Role_DisclosureTransformationFacilityRestructuringAndSeveranceChargesScheduleOfComponentsOfRestructuringChargesDetails" xlink:type="simple"/>
  <link:roleRef roleURI="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureBusinessAcquisitionsAdditionalInformationDetails" xlink:href="smhi-20221231.xsd#Role_DisclosureBusinessAcquisitionsAdditionalInformationDetails" xlink:type="simple"/>
  <link:roleRef roleURI="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureBusinessAcquisitionsSummaryOfPurchasePriceAllocationOfAcquiredAssetsDetails" xlink:href="smhi-20221231.xsd#Role_DisclosureBusinessAcquisitionsSummaryOfPurchasePriceAllocationOfAcquiredAssetsDetails" xlink:type="simple"/>
  <link:roleRef roleURI="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureNoteReceivableAdditionalInformationDetails" xlink:href="smhi-20221231.xsd#Role_DisclosureNoteReceivableAdditionalInformationDetails" xlink:type="simple"/>
  <link:roleRef roleURI="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureEquipmentAcquisitionsAndDispositionsAdditionalInformationDetails" xlink:href="smhi-20221231.xsd#Role_DisclosureEquipmentAcquisitionsAndDispositionsAdditionalInformationDetails" xlink:type="simple"/>
  <link:roleRef roleURI="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureEquipmentAcquisitionsAndDispositionsScheduleOfVesselAcquiredAndDisposedDetails" xlink:href="smhi-20221231.xsd#Role_DisclosureEquipmentAcquisitionsAndDispositionsScheduleOfVesselAcquiredAndDisposedDetails" xlink:type="simple"/>
  <link:roleRef roleURI="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureEquipmentAcquisitionsAndDispositionsScheduleOfVesselAcquiredAndDisposedParentheticalDetails" xlink:href="smhi-20221231.xsd#Role_DisclosureEquipmentAcquisitionsAndDispositionsScheduleOfVesselAcquiredAndDisposedParentheticalDetails" xlink:type="simple"/>
  <link:roleRef roleURI="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureEquipmentAcquisitionsAndDispositionsScheduleOfGainOnSaleOfWindcatWorkboatsDetails" xlink:href="smhi-20221231.xsd#Role_DisclosureEquipmentAcquisitionsAndDispositionsScheduleOfGainOnSaleOfWindcatWorkboatsDetails" xlink:type="simple"/>
  <link:roleRef roleURI="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureInvestmentsAtEquityAndAdvancesTo50OrLessOwnedCompaniesScheduleOfEquityInvestmentsDetails" xlink:href="smhi-20221231.xsd#Role_DisclosureInvestmentsAtEquityAndAdvancesTo50OrLessOwnedCompaniesScheduleOfEquityInvestmentsDetails" xlink:type="simple"/>
  <link:roleRef roleURI="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureInvestmentsAtEquityAndAdvancesTo50OrLessOwnedCompaniesAdditionalInformationDetails" xlink:href="smhi-20221231.xsd#Role_DisclosureInvestmentsAtEquityAndAdvancesTo50OrLessOwnedCompaniesAdditionalInformationDetails" xlink:type="simple"/>
  <link:roleRef roleURI="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureLeasesAdditionalInformationDetails" xlink:href="smhi-20221231.xsd#Role_DisclosureLeasesAdditionalInformationDetails" xlink:type="simple"/>
  <link:roleRef roleURI="http://www.seacormarine.com/20221231/taxonomy/role/DisclosureLeasesSummaryOfFutureMinimumPaymentsForLeasesParentheticalDetails" xlink:href="smhi-20221231.xsd#DisclosureLeasesSummaryOfFutureMinimumPaymentsForLeasesParentheticalDetails" xlink:type="simple"/>
  <link:roleRef roleURI="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureLongTermDebtScheduleOfLongTermDebtObligationsDetails" xlink:href="smhi-20221231.xsd#Role_DisclosureLongTermDebtScheduleOfLongTermDebtObligationsDetails" xlink:type="simple"/>
  <link:roleRef roleURI="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureLongTermDebtScheduleOfLongTermDebtObligationsParentheticalDetails" xlink:href="smhi-20221231.xsd#Role_DisclosureLongTermDebtScheduleOfLongTermDebtObligationsParentheticalDetails" xlink:type="simple"/>
  <link:roleRef roleURI="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureLongTermDebtAdditionalInformationDetails" xlink:href="smhi-20221231.xsd#Role_DisclosureLongTermDebtAdditionalInformationDetails" xlink:type="simple"/>
  <link:roleRef roleURI="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureLongTermDebtScheduleOfGainOnTransactionsUnderConditionalPayoffAgreementDetails" xlink:href="smhi-20221231.xsd#Role_DisclosureLongTermDebtScheduleOfGainOnTransactionsUnderConditionalPayoffAgreementDetails" xlink:type="simple"/>
  <link:roleRef roleURI="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureIncomeTaxesAdditionalInformationDetails" xlink:href="smhi-20221231.xsd#Role_DisclosureIncomeTaxesAdditionalInformationDetails" xlink:type="simple"/>
  <link:roleRef roleURI="http://www.seacormarine.com/20221231/taxonomy/role/DisclosureIncomeTaxesScheduleOfLossIncomeBeforeIncomeTaxExpenseBenefitDetails" xlink:href="smhi-20221231.xsd#DisclosureIncomeTaxesScheduleOfLossIncomeBeforeIncomeTaxExpenseBenefitDetails" xlink:type="simple"/>
  <link:roleRef roleURI="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureDerivativeInstrumentsAndHedgingStrategiesScheduleOfFairValueOfDerivativeAssetsAndLiabilitiesDetails" xlink:href="smhi-20221231.xsd#Role_DisclosureDerivativeInstrumentsAndHedgingStrategiesScheduleOfFairValueOfDerivativeAssetsAndLiabilitiesDetails" xlink:type="simple"/>
  <link:roleRef roleURI="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureDerivativeInstrumentsAndHedgingStrategiesAdditionalInformationDetails" xlink:href="smhi-20221231.xsd#Role_DisclosureDerivativeInstrumentsAndHedgingStrategiesAdditionalInformationDetails" xlink:type="simple"/>
  <link:roleRef roleURI="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureDerivativeInstrumentsAndHedgingStrategiesEffectOfDerivativeInstrumentsOnOtherComprehensiveIncomeLossDetails" xlink:href="smhi-20221231.xsd#Role_DisclosureDerivativeInstrumentsAndHedgingStrategiesEffectOfDerivativeInstrumentsOnOtherComprehensiveIncomeLossDetails" xlink:type="simple"/>
  <link:roleRef roleURI="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureDerivativeInstrumentsAndHedgingStrategiesScheduleOfGainsLossesOnDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsDetails" xlink:href="smhi-20221231.xsd#Role_DisclosureDerivativeInstrumentsAndHedgingStrategiesScheduleOfGainsLossesOnDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsDetails" xlink:type="simple"/>
  <link:roleRef roleURI="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureFairValueMeasurementsScheduleOfFairValueOfAssetsAndLiabilitiesMeasuredOnRecurringBasisDetails" xlink:href="smhi-20221231.xsd#Role_DisclosureFairValueMeasurementsScheduleOfFairValueOfAssetsAndLiabilitiesMeasuredOnRecurringBasisDetails" xlink:type="simple"/>
  <link:roleRef roleURI="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureFairValueMeasurementsScheduleOfEstimatedFairValuesOfFinancialAssetsAndLiabilitiesDetails" xlink:href="smhi-20221231.xsd#Role_DisclosureFairValueMeasurementsScheduleOfEstimatedFairValuesOfFinancialAssetsAndLiabilitiesDetails" xlink:type="simple"/>
  <link:roleRef roleURI="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureFairValueMeasurementsAdditionalInformationDetails" xlink:href="smhi-20221231.xsd#Role_DisclosureFairValueMeasurementsAdditionalInformationDetails" xlink:type="simple"/>
  <link:roleRef roleURI="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureWarrantsAdditionalInformationDetails" xlink:href="smhi-20221231.xsd#Role_DisclosureWarrantsAdditionalInformationDetails" xlink:type="simple"/>
  <link:roleRef roleURI="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureStockholdersEquityAdditionalInformationDetails" xlink:href="smhi-20221231.xsd#Role_DisclosureStockholdersEquityAdditionalInformationDetails" xlink:type="simple"/>
  <link:roleRef roleURI="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureNoncontrollingInterestsInSubsidiariesScheduleOfNoncontrollingInterestsInCompanySConsolidatedSubsidiariesDetails" xlink:href="smhi-20221231.xsd#Role_DisclosureNoncontrollingInterestsInSubsidiariesScheduleOfNoncontrollingInterestsInCompanySConsolidatedSubsidiariesDetails" xlink:type="simple"/>
  <link:roleRef roleURI="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureSavingsAndMultiEmployerPensionPlansAdditionalInformationDetails" xlink:href="smhi-20221231.xsd#Role_DisclosureSavingsAndMultiEmployerPensionPlansAdditionalInformationDetails" xlink:type="simple"/>
  <link:roleRef roleURI="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureShareBasedCompensationAdditionalInformationDetails" xlink:href="smhi-20221231.xsd#Role_DisclosureShareBasedCompensationAdditionalInformationDetails" xlink:type="simple"/>
  <link:roleRef roleURI="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureShareBasedCompensationScheduleOfEquityIncentivePlanTransactionsDetails" xlink:href="smhi-20221231.xsd#Role_DisclosureShareBasedCompensationScheduleOfEquityIncentivePlanTransactionsDetails" xlink:type="simple"/>
  <link:roleRef roleURI="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureShareBasedCompensationScheduleOfEquityIncentivePlanTransactionsDetailsParenthetical" xlink:href="smhi-20221231.xsd#Role_DisclosureShareBasedCompensationScheduleOfEquityIncentivePlanTransactionsDetailsParenthetical" xlink:type="simple"/>
  <link:roleRef roleURI="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureShareBasedCompensationScheduleOfRestrictedStockTransactionsDetails" xlink:href="smhi-20221231.xsd#Role_DisclosureShareBasedCompensationScheduleOfRestrictedStockTransactionsDetails" xlink:type="simple"/>
  <link:roleRef roleURI="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureRelatedPartyTransactionsAdditionalInformationDetails" xlink:href="smhi-20221231.xsd#Role_DisclosureRelatedPartyTransactionsAdditionalInformationDetails" xlink:type="simple"/>
  <link:roleRef roleURI="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureCommitmentsAndContingenciesAdditionalInformationDetails" xlink:href="smhi-20221231.xsd#Role_DisclosureCommitmentsAndContingenciesAdditionalInformationDetails" xlink:type="simple"/>
  <link:roleRef roleURI="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureMajorCustomersAndSegmentInformationAdditionalInformationDetails" xlink:href="smhi-20221231.xsd#Role_DisclosureMajorCustomersAndSegmentInformationAdditionalInformationDetails" xlink:type="simple"/>
  <link:roleRef roleURI="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureMajorCustomersAndSegmentInformationScheduleOfSegmentReportingInformationBySegmentDetails" xlink:href="smhi-20221231.xsd#Role_DisclosureMajorCustomersAndSegmentInformationScheduleOfSegmentReportingInformationBySegmentDetails" xlink:type="simple"/>
  <link:roleRef roleURI="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureMajorCustomersAndSegmentInformationScheduleOfSegmentReportingInformationBySegmentParentheticalDetails" xlink:href="smhi-20221231.xsd#Role_DisclosureMajorCustomersAndSegmentInformationScheduleOfSegmentReportingInformationBySegmentParentheticalDetails" xlink:type="simple"/>
  <link:roleRef roleURI="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureDiscontinuedOperationsAdditionalInformationDetails" xlink:href="smhi-20221231.xsd#Role_DisclosureDiscontinuedOperationsAdditionalInformationDetails" xlink:type="simple"/>
  <link:roleRef roleURI="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureDiscontinuedOperationsScheduleOfAssetsHeldForSaleDetails" xlink:href="smhi-20221231.xsd#Role_DisclosureDiscontinuedOperationsScheduleOfAssetsHeldForSaleDetails" xlink:type="simple"/>
  <link:roleRef roleURI="http://fasb.org/us-gaap/role/eedm/ExtensibleEnumerationLists" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-roles-2022.xsd#eedm" xlink:type="simple"/>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.seacormarine.com/20221231/taxonomy/role/Role_StatementConsolidatedStatementsOfComprehensiveIncomeLoss">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="us-gaap_IncomeStatementLocationAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OtherComprehensiveIncomeLossBeforeTaxPeriodIncreaseDecreaseAbstract" xlink:label="us-gaap_OtherComprehensiveIncomeLossBeforeTaxPeriodIncreaseDecreaseAbstract"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossBeforeReclassificationAndTax" xlink:label="us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossBeforeReclassificationAndTax"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="us-gaap_IncomeStatementLocationDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="us-gaap_IncomeStatementLocationDomain_default"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ProfitLoss" xlink:label="us-gaap_ProfitLoss"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_InterestExpenseMember" xlink:label="us-gaap_InterestExpenseMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax" xlink:label="us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_EquityMethodInvestments1Member" xlink:label="smhi_EquityMethodInvestments1Member"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax" xlink:label="us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OtherComprehensiveIncomeLossBeforeTax" xlink:label="us-gaap_OtherComprehensiveIncomeLossBeforeTax"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax" xlink:label="us-gaap_OtherComprehensiveIncomeLossNetOfTax"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest" xlink:label="us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest" xlink:label="us-gaap_ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ComprehensiveIncomeNetOfTax" xlink:label="us-gaap_ComprehensiveIncomeNetOfTax"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_IncomeStatementLocationAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_OtherComprehensiveIncomeLossBeforeTaxPeriodIncreaseDecreaseAbstract" xlink:to="us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossBeforeReclassificationAndTax" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_IncomeStatementLocationAxis" xlink:to="us-gaap_IncomeStatementLocationDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_IncomeStatementLocationAxis" xlink:to="us-gaap_IncomeStatementLocationDomain_default" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ProfitLoss" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncomeStatementLocationDomain" xlink:to="us-gaap_InterestExpenseMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_OtherComprehensiveIncomeLossBeforeTaxPeriodIncreaseDecreaseAbstract" xlink:to="us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_OtherComprehensiveIncomeLossBeforeTaxPeriodIncreaseDecreaseAbstract" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncomeStatementLocationDomain" xlink:to="smhi_EquityMethodInvestments1Member" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_OtherComprehensiveIncomeLossBeforeTaxPeriodIncreaseDecreaseAbstract" xlink:to="us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_OtherComprehensiveIncomeLossBeforeTaxPeriodIncreaseDecreaseAbstract" xlink:to="us-gaap_OtherComprehensiveIncomeLossBeforeTax" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_OtherComprehensiveIncomeLossBeforeTaxPeriodIncreaseDecreaseAbstract" xlink:to="us-gaap_OtherComprehensiveIncomeLossNetOfTax" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="5" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_OtherComprehensiveIncomeLossBeforeTaxPeriodIncreaseDecreaseAbstract" xlink:to="us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="6" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_OtherComprehensiveIncomeLossBeforeTaxPeriodIncreaseDecreaseAbstract" xlink:to="us-gaap_ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="7" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_OtherComprehensiveIncomeLossBeforeTaxPeriodIncreaseDecreaseAbstract" xlink:to="us-gaap_ComprehensiveIncomeNetOfTax" priority="2" use="optional"/>
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.seacormarine.com/20221231/taxonomy/role/Role_StatementConsolidatedStatementsOfChangesInEquity">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="us-gaap_StatementEquityComponentsAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RestatementAxis" xlink:label="srt_RestatementAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RestatementDomain" xlink:label="srt_RestatementDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RestatementDomain" xlink:label="srt_RestatementDomain_default"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EquityComponentDomain" xlink:label="us-gaap_EquityComponentDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EquityComponentDomain" xlink:label="us-gaap_EquityComponentDomain_default"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ScenarioPreviouslyReportedMember" xlink:label="srt_ScenarioPreviouslyReportedMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" xlink:label="us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommonStockMember" xlink:label="us-gaap_CommonStockMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="srt_TitleOfIndividualWithRelationshipToEntityDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_DirectorMember" xlink:label="srt_DirectorMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_TitleOfIndividualAxis" xlink:label="srt_TitleOfIndividualAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="srt_TitleOfIndividualWithRelationshipToEntityDomain_default"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommonStockSharesIssued" xlink:label="us-gaap_CommonStockSharesIssued"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AdditionalPaidInCapitalMember" xlink:label="us-gaap_AdditionalPaidInCapitalMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardGross" xlink:label="us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardGross"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TreasuryStockMember" xlink:label="us-gaap_TreasuryStockMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardGross" xlink:label="us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardGross"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RetainedEarningsMember" xlink:label="us-gaap_RetainedEarningsMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardForfeitures" xlink:label="us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardForfeitures"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember" xlink:label="us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardForfeited" xlink:label="us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardForfeited"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_NoncontrollingInterestMember" xlink:label="us-gaap_NoncontrollingInterestMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue" xlink:label="us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised" xlink:label="us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" xlink:label="us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_StockRepurchasedDuringPeriodValueExerciseOfWarrants" xlink:label="smhi_StockRepurchasedDuringPeriodValueExerciseOfWarrants"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_StockRepurchasedDuringPeriodSharesExerciseOfWarrants" xlink:label="smhi_StockRepurchasedDuringPeriodSharesExerciseOfWarrants"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TreasuryStockValueAcquiredCostMethod" xlink:label="us-gaap_TreasuryStockValueAcquiredCostMethod"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TreasuryStockSharesAcquired" xlink:label="us-gaap_TreasuryStockSharesAcquired"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockIssuedDuringPeriodValueIssuedForServices" xlink:label="us-gaap_StockIssuedDuringPeriodValueIssuedForServices"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockIssuedDuringPeriodSharesIssuedForServices" xlink:label="us-gaap_StockIssuedDuringPeriodSharesIssuedForServices"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockGrantedDuringPeriodValueSharebasedCompensation" xlink:label="us-gaap_StockGrantedDuringPeriodValueSharebasedCompensation"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_StockGrantedDuringPeriodSharesShareBasedCompensation" xlink:label="smhi_StockGrantedDuringPeriodSharesShareBasedCompensation"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockIssuedDuringPeriodValueAcquisitions" xlink:label="us-gaap_StockIssuedDuringPeriodValueAcquisitions"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockIssuedDuringPeriodSharesAcquisitions" xlink:label="us-gaap_StockIssuedDuringPeriodSharesAcquisitions"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_SaleOfWindcatWorkboats" xlink:label="smhi_SaleOfWindcatWorkboats"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ProfitLoss" xlink:label="us-gaap_ProfitLoss"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_OtherComprehensiveIncomeLossReclassificationNetOfTax" xlink:label="smhi_OtherComprehensiveIncomeLossReclassificationNetOfTax"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementEquityComponentsAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_RestatementAxis" xlink:to="srt_RestatementDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="srt_RestatementAxis" xlink:to="srt_RestatementDomain_default" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementEquityComponentsAxis" xlink:to="us-gaap_EquityComponentDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementEquityComponentsAxis" xlink:to="us-gaap_EquityComponentDomain_default" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_RestatementDomain" xlink:to="srt_ScenarioPreviouslyReportedMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_CommonStockMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_TitleOfIndividualWithRelationshipToEntityDomain" xlink:to="srt_DirectorMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_TitleOfIndividualAxis" xlink:to="srt_TitleOfIndividualWithRelationshipToEntityDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="srt_TitleOfIndividualAxis" xlink:to="srt_TitleOfIndividualWithRelationshipToEntityDomain_default" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="srt_RestatementAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_CommonStockSharesIssued" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_AdditionalPaidInCapitalMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="srt_TitleOfIndividualAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardGross" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_TreasuryStockMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardGross" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_RetainedEarningsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardForfeitures" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_AccumulatedOtherComprehensiveIncomeMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="5" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardForfeited" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="5" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_NoncontrollingInterestMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="6" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="7" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="8" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="9" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="smhi_StockRepurchasedDuringPeriodValueExerciseOfWarrants" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="10" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="smhi_StockRepurchasedDuringPeriodSharesExerciseOfWarrants" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="11" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_TreasuryStockValueAcquiredCostMethod" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="12" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_TreasuryStockSharesAcquired" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="13" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StockIssuedDuringPeriodValueIssuedForServices" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="14" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StockIssuedDuringPeriodSharesIssuedForServices" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="15" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StockGrantedDuringPeriodValueSharebasedCompensation" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="16" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="smhi_StockGrantedDuringPeriodSharesShareBasedCompensation" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="17" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StockIssuedDuringPeriodValueAcquisitions" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="18" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StockIssuedDuringPeriodSharesAcquisitions" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="19" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="smhi_SaleOfWindcatWorkboats" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="20" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ProfitLoss" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="21" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="smhi_OtherComprehensiveIncomeLossReclassificationNetOfTax" priority="2" use="optional"/>
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.seacormarine.com/20221231/taxonomy/role/Role_StatementConsolidatedStatementsOfChangesInEquityParenthetical">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeAxis" xlink:label="srt_RangeAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeMember" xlink:label="srt_RangeMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeMember" xlink:label="srt_RangeMember_default"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_MaximumMember" xlink:label="srt_MaximumMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_OwnershipPercentage" xlink:label="smhi_OwnershipPercentage"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_MinimumMember" xlink:label="srt_MinimumMember"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="srt_RangeAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_RangeAxis" xlink:to="srt_RangeMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="srt_RangeAxis" xlink:to="srt_RangeMember_default" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_RangeMember" xlink:to="srt_MaximumMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="smhi_OwnershipPercentage" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_RangeMember" xlink:to="srt_MinimumMember" priority="2" use="optional"/>
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureBusinessAcquisitionsTables">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xlink:label="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_EquityMethodInvesteeNameDomain" xlink:label="srt_EquityMethodInvesteeNameDomain"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_OSVPartnersMember" xlink:label="smhi_OSVPartnersMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_EquityMethodInvesteeNameDomain" xlink:label="srt_EquityMethodInvesteeNameDomain_default"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfRecognizedIdentifiedAssetsAcquiredAndLiabilitiesAssumedTableTextBlock" xlink:label="us-gaap_ScheduleOfRecognizedIdentifiedAssetsAcquiredAndLiabilitiesAssumedTableTextBlock"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_EquityMethodInvesteeNameDomain" xlink:to="smhi_OSVPartnersMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xlink:to="srt_EquityMethodInvesteeNameDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xlink:to="srt_EquityMethodInvesteeNameDomain_default" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ScheduleOfRecognizedIdentifiedAssetsAcquiredAndLiabilitiesAssumedTableTextBlock" priority="2" use="optional"/>
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureNatureOfOperationsAndAccountingPoliciesAdditionalInformationDetails">
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_NatureOfOperationsAndAccountingPoliciesLineItems" xlink:label="smhi_NatureOfOperationsAndAccountingPoliciesLineItems"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_NatureOfOperationsAndAccountingPoliciesTable" xlink:label="smhi_NatureOfOperationsAndAccountingPoliciesTable"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ImpairedLongLivedAssetsHeldAndUsedByTypeAxis" xlink:label="us-gaap_ImpairedLongLivedAssetsHeldAndUsedByTypeAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ImpairedLongLivedAssetsHeldAndUsedAssetNameDomain" xlink:label="us-gaap_ImpairedLongLivedAssetsHeldAndUsedAssetNameDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ImpairedLongLivedAssetsHeldAndUsedAssetNameDomain" xlink:label="us-gaap_ImpairedLongLivedAssetsHeldAndUsedAssetNameDomain_default"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ReclassificationTypeDomain" xlink:label="us-gaap_ReclassificationTypeDomain"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_ContractCompletionsAndCertainReclassificationsMember" xlink:label="smhi_ContractCompletionsAndCertainReclassificationsMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_StatementGeographicalAxis" xlink:label="srt_StatementGeographicalAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_CumulativeEffectPeriodOfAdoptionAxis" xlink:label="srt_CumulativeEffectPeriodOfAdoptionAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_CumulativeEffectPeriodOfAdoptionDomain" xlink:label="srt_CumulativeEffectPeriodOfAdoptionDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_CumulativeEffectPeriodOfAdoptionDomain" xlink:label="srt_CumulativeEffectPeriodOfAdoptionDomain_default"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_EquityMethodInvesteeNameDomain" xlink:label="srt_EquityMethodInvesteeNameDomain"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_MexMarMember" xlink:label="smhi_MexMarMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementOperatingActivitiesSegmentAxis" xlink:label="us-gaap_StatementOperatingActivitiesSegmentAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SegmentOperatingActivitiesDomain" xlink:label="us-gaap_SegmentOperatingActivitiesDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SegmentOperatingActivitiesDomain" xlink:label="us-gaap_SegmentOperatingActivitiesDomain_default"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeAxis" xlink:label="srt_RangeAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeMember" xlink:label="srt_RangeMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ReclassificationTypeAxis" xlink:label="us-gaap_ReclassificationTypeAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ReclassificationTypeDomain" xlink:label="us-gaap_ReclassificationTypeDomain_default"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_SegmentGeographicalDomain" xlink:label="srt_SegmentGeographicalDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/country/2022/country-2022.xsd#country_US" xlink:label="country_US"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_MinimumMember" xlink:label="srt_MinimumMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain_default"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis" xlink:label="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AntidilutiveSecuritiesNameDomain" xlink:label="us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AntidilutiveSecuritiesNameDomain" xlink:label="us-gaap_AntidilutiveSecuritiesNameDomain_default"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_FastSupportVesselMember" xlink:label="smhi_FastSupportVesselMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_BalanceSheetLocationDomain" xlink:label="us-gaap_BalanceSheetLocationDomain"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_PrepaidCharterModificationAndReservationMember" xlink:label="smhi_PrepaidCharterModificationAndReservationMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_GeographicDistributionAxis" xlink:label="us-gaap_GeographicDistributionAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_GeographicDistributionDomain" xlink:label="us-gaap_GeographicDistributionDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_GeographicDistributionDomain" xlink:label="us-gaap_GeographicDistributionDomain_default"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember" xlink:label="srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TypeOfAdoptionMember" xlink:label="us-gaap_TypeOfAdoptionMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AccountingStandardsUpdate201602Member" xlink:label="us-gaap_AccountingStandardsUpdate201602Member"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xlink:label="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PerformanceSharesMember" xlink:label="us-gaap_PerformanceSharesMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_SegmentGeographicalDomain" xlink:label="srt_SegmentGeographicalDomain_default"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_NumberOfReportableSegments" xlink:label="us-gaap_NumberOfReportableSegments"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" xlink:label="us-gaap_AdjustmentsForNewAccountingPronouncementsAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TypeOfAdoptionMember" xlink:label="us-gaap_TypeOfAdoptionMember_default"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AwardTypeAxis" xlink:label="us-gaap_AwardTypeAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_default"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_GeographicDistributionDomesticMember" xlink:label="us-gaap_GeographicDistributionDomesticMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SegmentContinuingOperationsMember" xlink:label="us-gaap_SegmentContinuingOperationsMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis" xlink:label="us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ChangeInAccountingPrincipleMember" xlink:label="us-gaap_ChangeInAccountingPrincipleMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ChangeInAccountingPrincipleMember" xlink:label="us-gaap_ChangeInAccountingPrincipleMember_default"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:label="us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="us-gaap_PropertyPlantAndEquipmentTypeDomain_default"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RestrictedStockMember" xlink:label="us-gaap_RestrictedStockMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_SEACORMarineForeignHoldingsMember" xlink:label="smhi_SEACORMarineForeignHoldingsMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_ChangeInAccountingPrincipleForEquipmentOfficeAndLandLeasesMember" xlink:label="smhi_ChangeInAccountingPrincipleForEquipmentOfficeAndLandLeasesMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_BalanceSheetLocationAxis" xlink:label="us-gaap_BalanceSheetLocationAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_BalanceSheetLocationDomain" xlink:label="us-gaap_BalanceSheetLocationDomain_default"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_OffshoreSupportVesselsMember" xlink:label="smhi_OffshoreSupportVesselsMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_OVHMember" xlink:label="smhi_OVHMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_AfricaAndEuropeMember" xlink:label="smhi_AfricaAndEuropeMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_MaximumMember" xlink:label="srt_MaximumMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_AnchorHandlingTowingSupplyVesselMember" xlink:label="smhi_AnchorHandlingTowingSupplyVesselMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_PrepaidVesselManagementFeesMember" xlink:label="smhi_PrepaidVesselManagementFeesMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AccountingStandardsUpdate202006Member" xlink:label="us-gaap_AccountingStandardsUpdate202006Member"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_NumberOfVessels" xlink:label="smhi_NumberOfVessels"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SegmentDiscontinuedOperationsMember" xlink:label="us-gaap_SegmentDiscontinuedOperationsMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EmployeeStockOptionMember" xlink:label="us-gaap_EmployeeStockOptionMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_ChangeInAccountingPrincipleForUnamortizedDeferredGainsMember" xlink:label="smhi_ChangeInAccountingPrincipleForUnamortizedDeferredGainsMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_EmergencyResponseAndRescueVesselMember" xlink:label="smhi_EmergencyResponseAndRescueVesselMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_SEACORMarlinLLCMember" xlink:label="smhi_SEACORMarlinLLCMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_MiddleEastAndAsiaMember" xlink:label="smhi_MiddleEastAndAsiaMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_TowerAndGangwayMember" xlink:label="smhi_TowerAndGangwayMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AccountingStandardsUpdate202010Member" xlink:label="us-gaap_AccountingStandardsUpdate202010Member"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_NumberOfVesselsOwned" xlink:label="smhi_NumberOfVesselsOwned"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ConvertibleDebtSecuritiesMember" xlink:label="us-gaap_ConvertibleDebtSecuritiesMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_LiftboatVesselsMember" xlink:label="smhi_LiftboatVesselsMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_EquityInvestmentsIn50OrLessOwnedCompaniesMember" xlink:label="smhi_EquityInvestmentsIn50OrLessOwnedCompaniesMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_LatinAmericaMember" xlink:label="srt_LatinAmericaMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AccountingStandardsUpdate201912Member" xlink:label="us-gaap_AccountingStandardsUpdate201912Member"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_NumberOfVesselsLeasedIn" xlink:label="smhi_NumberOfVesselsLeasedIn"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_SpecialtyVesselMember" xlink:label="smhi_SpecialtyVesselMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_NumberOfVesselsManagedIn" xlink:label="smhi_NumberOfVesselsManagedIn"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_VesselUnderConstructionMember" xlink:label="smhi_VesselUnderConstructionMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_NumberOfVesselsJointVentured" xlink:label="smhi_NumberOfVesselsJointVentured"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_VesselsMember" xlink:label="smhi_VesselsMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EquityMethodInvestmentOwnershipPercentage" xlink:label="us-gaap_EquityMethodInvestmentOwnershipPercentage"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ContractWithCustomerLiability" xlink:label="us-gaap_ContractWithCustomerLiability"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ContractWithCustomerLiabilityRevenueRecognized" xlink:label="us-gaap_ContractWithCustomerLiabilityRevenueRecognized"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_InventoryValuationReserves" xlink:label="us-gaap_InventoryValuationReserves"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentUsefulLife" xlink:label="us-gaap_PropertyPlantAndEquipmentUsefulLife"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_Depreciation" xlink:label="us-gaap_Depreciation"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_PropertyPlantAndEquipmentExcludingConstructionInProgress" xlink:label="smhi_PropertyPlantAndEquipmentExcludingConstructionInProgress"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_InterestCostsIncurredCapitalized" xlink:label="us-gaap_InterestCostsIncurredCapitalized"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ImpairmentOfLongLivedAssetsHeldForUse" xlink:label="us-gaap_ImpairmentOfLongLivedAssetsHeldForUse"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ImpairmentLongLivedAssetHeldForUseStatementOfIncomeOrComprehensiveIncomeExtensibleEnumeration" xlink:label="us-gaap_ImpairmentLongLivedAssetHeldForUseStatementOfIncomeOrComprehensiveIncomeExtensibleEnumeration"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ImpairmentOfLongLivedAssetsToBeDisposedOf" xlink:label="us-gaap_ImpairmentOfLongLivedAssetsToBeDisposedOf"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_UnearnedRevenueRelatedToNewContractAgreements" xlink:label="smhi_UnearnedRevenueRelatedToNewContractAgreements"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_UnearnedRevenuePreviouslyRecordedRecognized" xlink:label="smhi_UnearnedRevenuePreviouslyRecordedRecognized"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DeferredRevenue" xlink:label="us-gaap_DeferredRevenue"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_CostsForDrydockingAndRepairExpendituresIncurred" xlink:label="smhi_CostsForDrydockingAndRepairExpendituresIncurred"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_GainContingencyOnCostsForDrydockingAndRepairExpendituresIncurred" xlink:label="smhi_GainContingencyOnCostsForDrydockingAndRepairExpendituresIncurred"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired" xlink:label="us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_PartialImpairmentOfRightToUseAssets" xlink:label="smhi_PartialImpairmentOfRightToUseAssets"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_AdditionalImpairmentOfRightToUseAssets" xlink:label="smhi_AdditionalImpairmentOfRightToUseAssets"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EquityMethodInvestmentOtherThanTemporaryImpairment" xlink:label="us-gaap_EquityMethodInvestmentOtherThanTemporaryImpairment"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_ReclassOfGainToRetainedEarnings" xlink:label="smhi_ReclassOfGainToRetainedEarnings"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_DeferredGainOnSaleOfPropertyOtherAdjustments" xlink:label="smhi_DeferredGainOnSaleOfPropertyOtherAdjustments"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncrementalCommonSharesAttributableToConversionOfDebtSecurities" xlink:label="us-gaap_IncrementalCommonSharesAttributableToConversionOfDebtSecurities"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1" xlink:label="us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount" xlink:label="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment" xlink:label="us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ChangeInAccountingPrincipleAccountingStandardsUpdateAdopted" xlink:label="us-gaap_ChangeInAccountingPrincipleAccountingStandardsUpdateAdopted"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ChangeInAccountingPrincipleAccountingStandardsUpdateAdoptionDate" xlink:label="us-gaap_ChangeInAccountingPrincipleAccountingStandardsUpdateAdoptionDate"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ChangeInAccountingPrincipleAccountingStandardsUpdateImmaterialEffect" xlink:label="us-gaap_ChangeInAccountingPrincipleAccountingStandardsUpdateImmaterialEffect"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="smhi_NatureOfOperationsAndAccountingPoliciesLineItems" xlink:to="smhi_NatureOfOperationsAndAccountingPoliciesTable" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_ImpairedLongLivedAssetsHeldAndUsedByTypeAxis" xlink:to="us-gaap_ImpairedLongLivedAssetsHeldAndUsedAssetNameDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_ImpairedLongLivedAssetsHeldAndUsedByTypeAxis" xlink:to="us-gaap_ImpairedLongLivedAssetsHeldAndUsedAssetNameDomain_default" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ReclassificationTypeDomain" xlink:to="smhi_ContractCompletionsAndCertainReclassificationsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="smhi_NatureOfOperationsAndAccountingPoliciesTable" xlink:to="srt_StatementGeographicalAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_CumulativeEffectPeriodOfAdoptionAxis" xlink:to="srt_CumulativeEffectPeriodOfAdoptionDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="srt_CumulativeEffectPeriodOfAdoptionAxis" xlink:to="srt_CumulativeEffectPeriodOfAdoptionDomain_default" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_EquityMethodInvesteeNameDomain" xlink:to="smhi_MexMarMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementOperatingActivitiesSegmentAxis" xlink:to="us-gaap_SegmentOperatingActivitiesDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementOperatingActivitiesSegmentAxis" xlink:to="us-gaap_SegmentOperatingActivitiesDomain_default" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_RangeAxis" xlink:to="srt_RangeMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_ReclassificationTypeAxis" xlink:to="us-gaap_ReclassificationTypeDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_ReclassificationTypeAxis" xlink:to="us-gaap_ReclassificationTypeDomain_default" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_SegmentGeographicalDomain" xlink:to="country_US" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_RangeMember" xlink:to="srt_MinimumMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain_default" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis" xlink:to="us-gaap_AntidilutiveSecuritiesNameDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis" xlink:to="us-gaap_AntidilutiveSecuritiesNameDomain_default" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ImpairedLongLivedAssetsHeldAndUsedAssetNameDomain" xlink:to="smhi_FastSupportVesselMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_BalanceSheetLocationDomain" xlink:to="smhi_PrepaidCharterModificationAndReservationMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_GeographicDistributionAxis" xlink:to="us-gaap_GeographicDistributionDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_GeographicDistributionAxis" xlink:to="us-gaap_GeographicDistributionDomain_default" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_CumulativeEffectPeriodOfAdoptionDomain" xlink:to="srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_TypeOfAdoptionMember" xlink:to="us-gaap_AccountingStandardsUpdate201602Member" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xlink:to="srt_EquityMethodInvesteeNameDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="us-gaap_PerformanceSharesMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_StatementGeographicalAxis" xlink:to="srt_SegmentGeographicalDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="srt_StatementGeographicalAxis" xlink:to="srt_SegmentGeographicalDomain_default" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_NatureOfOperationsAndAccountingPoliciesLineItems" xlink:to="us-gaap_NumberOfReportableSegments" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" xlink:to="us-gaap_TypeOfAdoptionMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" xlink:to="us-gaap_TypeOfAdoptionMember_default" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_AwardTypeAxis" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_AwardTypeAxis" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_default" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_GeographicDistributionDomain" xlink:to="us-gaap_GeographicDistributionDomesticMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentOperatingActivitiesDomain" xlink:to="us-gaap_SegmentContinuingOperationsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis" xlink:to="us-gaap_ChangeInAccountingPrincipleMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis" xlink:to="us-gaap_ChangeInAccountingPrincipleMember_default" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:to="us-gaap_PropertyPlantAndEquipmentTypeDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:to="us-gaap_PropertyPlantAndEquipmentTypeDomain_default" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AntidilutiveSecuritiesNameDomain" xlink:to="us-gaap_RestrictedStockMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_EntityDomain" xlink:to="smhi_SEACORMarineForeignHoldingsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ChangeInAccountingPrincipleMember" xlink:to="smhi_ChangeInAccountingPrincipleForEquipmentOfficeAndLandLeasesMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_BalanceSheetLocationAxis" xlink:to="us-gaap_BalanceSheetLocationDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_BalanceSheetLocationAxis" xlink:to="us-gaap_BalanceSheetLocationDomain_default" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="smhi_OffshoreSupportVesselsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="smhi_NatureOfOperationsAndAccountingPoliciesTable" xlink:to="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_EquityMethodInvesteeNameDomain" xlink:to="smhi_OVHMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_SegmentGeographicalDomain" xlink:to="smhi_AfricaAndEuropeMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_RangeMember" xlink:to="srt_MaximumMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ImpairedLongLivedAssetsHeldAndUsedAssetNameDomain" xlink:to="smhi_AnchorHandlingTowingSupplyVesselMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_BalanceSheetLocationDomain" xlink:to="smhi_PrepaidVesselManagementFeesMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_TypeOfAdoptionMember" xlink:to="us-gaap_AccountingStandardsUpdate202006Member" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_NatureOfOperationsAndAccountingPoliciesLineItems" xlink:to="smhi_NumberOfVessels" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentOperatingActivitiesDomain" xlink:to="us-gaap_SegmentDiscontinuedOperationsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AntidilutiveSecuritiesNameDomain" xlink:to="us-gaap_EmployeeStockOptionMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ChangeInAccountingPrincipleMember" xlink:to="smhi_ChangeInAccountingPrincipleForUnamortizedDeferredGainsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="smhi_EmergencyResponseAndRescueVesselMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="smhi_NatureOfOperationsAndAccountingPoliciesTable" xlink:to="srt_RangeAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_EquityMethodInvesteeNameDomain" xlink:to="smhi_SEACORMarlinLLCMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_SegmentGeographicalDomain" xlink:to="smhi_MiddleEastAndAsiaMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ImpairedLongLivedAssetsHeldAndUsedAssetNameDomain" xlink:to="smhi_TowerAndGangwayMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_TypeOfAdoptionMember" xlink:to="us-gaap_AccountingStandardsUpdate202010Member" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_NatureOfOperationsAndAccountingPoliciesLineItems" xlink:to="smhi_NumberOfVesselsOwned" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AntidilutiveSecuritiesNameDomain" xlink:to="us-gaap_ConvertibleDebtSecuritiesMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="smhi_LiftboatVesselsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="smhi_NatureOfOperationsAndAccountingPoliciesTable" xlink:to="dei_LegalEntityAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_EquityMethodInvesteeNameDomain" xlink:to="smhi_EquityInvestmentsIn50OrLessOwnedCompaniesMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_SegmentGeographicalDomain" xlink:to="srt_LatinAmericaMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_TypeOfAdoptionMember" xlink:to="us-gaap_AccountingStandardsUpdate201912Member" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_NatureOfOperationsAndAccountingPoliciesLineItems" xlink:to="smhi_NumberOfVesselsLeasedIn" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="smhi_SpecialtyVesselMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="smhi_NatureOfOperationsAndAccountingPoliciesTable" xlink:to="us-gaap_GeographicDistributionAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_NatureOfOperationsAndAccountingPoliciesLineItems" xlink:to="smhi_NumberOfVesselsManagedIn" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="smhi_VesselUnderConstructionMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="5" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="smhi_NatureOfOperationsAndAccountingPoliciesTable" xlink:to="us-gaap_BalanceSheetLocationAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="5" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_NatureOfOperationsAndAccountingPoliciesLineItems" xlink:to="smhi_NumberOfVesselsJointVentured" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="5" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="smhi_VesselsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="6" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="smhi_NatureOfOperationsAndAccountingPoliciesTable" xlink:to="us-gaap_ReclassificationTypeAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="6" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_NatureOfOperationsAndAccountingPoliciesLineItems" xlink:to="us-gaap_EquityMethodInvestmentOwnershipPercentage" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="7" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="smhi_NatureOfOperationsAndAccountingPoliciesTable" xlink:to="us-gaap_PropertyPlantAndEquipmentByTypeAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="7" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_NatureOfOperationsAndAccountingPoliciesLineItems" xlink:to="us-gaap_ContractWithCustomerLiability" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="8" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="smhi_NatureOfOperationsAndAccountingPoliciesTable" xlink:to="us-gaap_StatementOperatingActivitiesSegmentAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="8" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_NatureOfOperationsAndAccountingPoliciesLineItems" xlink:to="us-gaap_ContractWithCustomerLiabilityRevenueRecognized" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="9" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="smhi_NatureOfOperationsAndAccountingPoliciesTable" xlink:to="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="9" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_NatureOfOperationsAndAccountingPoliciesLineItems" xlink:to="us-gaap_InventoryValuationReserves" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="10" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="smhi_NatureOfOperationsAndAccountingPoliciesTable" xlink:to="us-gaap_ImpairedLongLivedAssetsHeldAndUsedByTypeAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="10" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_NatureOfOperationsAndAccountingPoliciesLineItems" xlink:to="us-gaap_PropertyPlantAndEquipmentUsefulLife" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="11" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="smhi_NatureOfOperationsAndAccountingPoliciesTable" xlink:to="us-gaap_AwardTypeAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="11" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_NatureOfOperationsAndAccountingPoliciesLineItems" xlink:to="us-gaap_Depreciation" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="12" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="smhi_NatureOfOperationsAndAccountingPoliciesTable" xlink:to="us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="12" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_NatureOfOperationsAndAccountingPoliciesLineItems" xlink:to="smhi_PropertyPlantAndEquipmentExcludingConstructionInProgress" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="13" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="smhi_NatureOfOperationsAndAccountingPoliciesTable" xlink:to="srt_CumulativeEffectPeriodOfAdoptionAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="13" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_NatureOfOperationsAndAccountingPoliciesLineItems" xlink:to="us-gaap_InterestCostsIncurredCapitalized" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="14" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="smhi_NatureOfOperationsAndAccountingPoliciesTable" xlink:to="us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="14" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_NatureOfOperationsAndAccountingPoliciesLineItems" xlink:to="us-gaap_ImpairmentOfLongLivedAssetsHeldForUse" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="15" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_NatureOfOperationsAndAccountingPoliciesLineItems" xlink:to="us-gaap_ImpairmentLongLivedAssetHeldForUseStatementOfIncomeOrComprehensiveIncomeExtensibleEnumeration" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="16" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_NatureOfOperationsAndAccountingPoliciesLineItems" xlink:to="us-gaap_ImpairmentOfLongLivedAssetsToBeDisposedOf" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="17" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_NatureOfOperationsAndAccountingPoliciesLineItems" xlink:to="smhi_UnearnedRevenueRelatedToNewContractAgreements" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="18" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_NatureOfOperationsAndAccountingPoliciesLineItems" xlink:to="smhi_UnearnedRevenuePreviouslyRecordedRecognized" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="19" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_NatureOfOperationsAndAccountingPoliciesLineItems" xlink:to="us-gaap_DeferredRevenue" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="20" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_NatureOfOperationsAndAccountingPoliciesLineItems" xlink:to="smhi_CostsForDrydockingAndRepairExpendituresIncurred" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="21" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_NatureOfOperationsAndAccountingPoliciesLineItems" xlink:to="smhi_GainContingencyOnCostsForDrydockingAndRepairExpendituresIncurred" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="22" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_NatureOfOperationsAndAccountingPoliciesLineItems" xlink:to="us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="23" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_NatureOfOperationsAndAccountingPoliciesLineItems" xlink:to="smhi_PartialImpairmentOfRightToUseAssets" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="24" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_NatureOfOperationsAndAccountingPoliciesLineItems" xlink:to="smhi_AdditionalImpairmentOfRightToUseAssets" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="25" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_NatureOfOperationsAndAccountingPoliciesLineItems" xlink:to="us-gaap_EquityMethodInvestmentOtherThanTemporaryImpairment" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="26" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_NatureOfOperationsAndAccountingPoliciesLineItems" xlink:to="smhi_ReclassOfGainToRetainedEarnings" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="27" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_NatureOfOperationsAndAccountingPoliciesLineItems" xlink:to="smhi_DeferredGainOnSaleOfPropertyOtherAdjustments" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="28" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_NatureOfOperationsAndAccountingPoliciesLineItems" xlink:to="us-gaap_IncrementalCommonSharesAttributableToConversionOfDebtSecurities" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="29" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_NatureOfOperationsAndAccountingPoliciesLineItems" xlink:to="us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="30" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_NatureOfOperationsAndAccountingPoliciesLineItems" xlink:to="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="31" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_NatureOfOperationsAndAccountingPoliciesLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="32" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_NatureOfOperationsAndAccountingPoliciesLineItems" xlink:to="us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="33" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_NatureOfOperationsAndAccountingPoliciesLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="34" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_NatureOfOperationsAndAccountingPoliciesLineItems" xlink:to="us-gaap_ChangeInAccountingPrincipleAccountingStandardsUpdateAdopted" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="35" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_NatureOfOperationsAndAccountingPoliciesLineItems" xlink:to="us-gaap_ChangeInAccountingPrincipleAccountingStandardsUpdateAdoptionDate" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="36" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_NatureOfOperationsAndAccountingPoliciesLineItems" xlink:to="us-gaap_ChangeInAccountingPrincipleAccountingStandardsUpdateImmaterialEffect" priority="2" use="optional"/>
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureNatureOfOperationsAndAccountingPoliciesSummaryOfPropertyAndEquipmentFromContinuingOperationsDetails">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:label="us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentGross" xlink:label="us-gaap_PropertyPlantAndEquipmentGross"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_OffshoreSupportVesselsAnchorHandlingTowingSupplyMember" xlink:label="smhi_OffshoreSupportVesselsAnchorHandlingTowingSupplyMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" xlink:label="us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_FastSupportVesselsMember" xlink:label="smhi_FastSupportVesselsMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_PropertyPlantAndEquipmentExcludingConstructionInProgress" xlink:label="smhi_PropertyPlantAndEquipmentExcludingConstructionInProgress"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_PlatformSupplyVesselsMember" xlink:label="smhi_PlatformSupplyVesselsMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_OffshoreSupportVesselsSupplyMember" xlink:label="smhi_OffshoreSupportVesselsSupplyMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_OffshoreSupportVesselsSpecialtyMember" xlink:label="smhi_OffshoreSupportVesselsSpecialtyMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_OffshoreSupportVesselsLiftboatsMember" xlink:label="smhi_OffshoreSupportVesselsLiftboatsMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_GeneralMachineryAndSparesMember" xlink:label="smhi_GeneralMachineryAndSparesMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentOtherTypesMember" xlink:label="us-gaap_PropertyPlantAndEquipmentOtherTypesMember"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_PropertyPlantAndEquipmentByTypeAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_PropertyPlantAndEquipmentGross" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:to="us-gaap_PropertyPlantAndEquipmentTypeDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="smhi_OffshoreSupportVesselsAnchorHandlingTowingSupplyMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="smhi_FastSupportVesselsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="smhi_PropertyPlantAndEquipmentExcludingConstructionInProgress" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="smhi_PlatformSupplyVesselsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="smhi_OffshoreSupportVesselsSupplyMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="smhi_OffshoreSupportVesselsSpecialtyMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="5" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="smhi_OffshoreSupportVesselsLiftboatsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="6" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="smhi_GeneralMachineryAndSparesMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="7" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="us-gaap_PropertyPlantAndEquipmentOtherTypesMember" priority="2" use="optional"/>
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureNatureOfOperationsAndAccountingPoliciesSummaryOfPropertyAndEquipmentFromContinuingOperationsParentheticalDetails">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:label="us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_CarryingValueOfAssetsHeldForSale" xlink:label="smhi_CarryingValueOfAssetsHeldForSale"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_OffshoreSupportVesselsLiftboatsMember" xlink:label="smhi_OffshoreSupportVesselsLiftboatsMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_NetProceedsFromSaleOfAssets" xlink:label="smhi_NetProceedsFromSaleOfAssets"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_BuildingMember" xlink:label="us-gaap_BuildingMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_GainsLossesOnSalesOfAssets" xlink:label="us-gaap_GainsLossesOnSalesOfAssets"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_TransactionCosts" xlink:label="smhi_TransactionCosts"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_PropertyPlantAndEquipmentByTypeAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="smhi_CarryingValueOfAssetsHeldForSale" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:to="us-gaap_PropertyPlantAndEquipmentTypeDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="smhi_OffshoreSupportVesselsLiftboatsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="smhi_NetProceedsFromSaleOfAssets" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="us-gaap_BuildingMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_GainsLossesOnSalesOfAssets" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="smhi_TransactionCosts" priority="2" use="optional"/>
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureNatureOfOperationsAndAccountingPoliciesScheduleOfAccumulatedOtherComprehensiveLossIncomeDetails">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems" xlink:label="us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossTable" xlink:label="us-gaap_AccumulatedOtherComprehensiveIncomeLossTable"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="us-gaap_StatementEquityComponentsAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EquityComponentDomain" xlink:label="us-gaap_EquityComponentDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AccumulatedTranslationAdjustmentMember" xlink:label="us-gaap_AccumulatedTranslationAdjustmentMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" xlink:label="us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember" xlink:label="us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OtherComprehensiveIncomeLossBeforeTax" xlink:label="us-gaap_OtherComprehensiveIncomeLossBeforeTax"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember" xlink:label="us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OtherComprehensiveIncomeLossTax" xlink:label="us-gaap_OtherComprehensiveIncomeLossTax"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AccumulatedForeignCurrencyAdjustmentAttributableToNoncontrollingInterestMember" xlink:label="us-gaap_AccumulatedForeignCurrencyAdjustmentAttributableToNoncontrollingInterestMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AccumulatedGainLossNetCashFlowHedgeNoncontrollingInterestMember" xlink:label="us-gaap_AccumulatedGainLossNetCashFlowHedgeNoncontrollingInterestMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AociAttributableToNoncontrollingInterestMember" xlink:label="us-gaap_AociAttributableToNoncontrollingInterestMember"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="us-gaap_AccumulatedOtherComprehensiveIncomeLossTable" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_AccumulatedOtherComprehensiveIncomeLossTable" xlink:to="us-gaap_StatementEquityComponentsAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementEquityComponentsAxis" xlink:to="us-gaap_EquityComponentDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_AccumulatedTranslationAdjustmentMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="us-gaap_OtherComprehensiveIncomeLossBeforeTax" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_AccumulatedOtherComprehensiveIncomeMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="us-gaap_OtherComprehensiveIncomeLossTax" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_AccumulatedForeignCurrencyAdjustmentAttributableToNoncontrollingInterestMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_AccumulatedGainLossNetCashFlowHedgeNoncontrollingInterestMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="5" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_AociAttributableToNoncontrollingInterestMember" priority="2" use="optional"/>
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureTransformationFacilityRestructuringAndSeveranceChargesAdditionalInformationDetails">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RestructuringCostAndReserveLineItems" xlink:label="us-gaap_RestructuringCostAndReserveLineItems"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable" xlink:label="us-gaap_ScheduleOfRestructuringAndRelatedCostsTable"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RestructuringPlanDomain" xlink:label="us-gaap_RestructuringPlanDomain"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_TransformationPlanMember" xlink:label="smhi_TransformationPlanMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RestructuringPlanAxis" xlink:label="us-gaap_RestructuringPlanAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RestructuringPlanDomain" xlink:label="us-gaap_RestructuringPlanDomain_default"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RestructuringAndRelatedActivitiesDescription" xlink:label="us-gaap_RestructuringAndRelatedActivitiesDescription"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RestructuringCosts" xlink:label="us-gaap_RestructuringCosts"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RestructuringReserve" xlink:label="us-gaap_RestructuringReserve"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RestructuringCharges" xlink:label="us-gaap_RestructuringCharges"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_SeveranceCharges" xlink:label="smhi_SeveranceCharges"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OtherRestructuringCosts" xlink:label="us-gaap_OtherRestructuringCosts"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_RestructuringCostAndReserveLineItems" xlink:to="us-gaap_ScheduleOfRestructuringAndRelatedCostsTable" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RestructuringPlanDomain" xlink:to="smhi_TransformationPlanMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_RestructuringPlanAxis" xlink:to="us-gaap_RestructuringPlanDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_RestructuringPlanAxis" xlink:to="us-gaap_RestructuringPlanDomain_default" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RestructuringCostAndReserveLineItems" xlink:to="us-gaap_RestructuringAndRelatedActivitiesDescription" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfRestructuringAndRelatedCostsTable" xlink:to="us-gaap_RestructuringPlanAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RestructuringCostAndReserveLineItems" xlink:to="us-gaap_RestructuringCosts" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RestructuringCostAndReserveLineItems" xlink:to="us-gaap_RestructuringReserve" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RestructuringCostAndReserveLineItems" xlink:to="us-gaap_RestructuringCharges" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RestructuringCostAndReserveLineItems" xlink:to="smhi_SeveranceCharges" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="5" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RestructuringCostAndReserveLineItems" xlink:to="us-gaap_OtherRestructuringCosts" priority="2" use="optional"/>
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureTransformationFacilityRestructuringAndSeveranceChargesScheduleOfComponentsOfRestructuringChargesDetails">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RestructuringCostAndReserveLineItems" xlink:label="us-gaap_RestructuringCostAndReserveLineItems"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable" xlink:label="us-gaap_ScheduleOfRestructuringAndRelatedCostsTable"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_SegmentGeographicalDomain" xlink:label="srt_SegmentGeographicalDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/country/2022/country-2022.xsd#country_US" xlink:label="country_US"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RestructuringPlanDomain" xlink:label="us-gaap_RestructuringPlanDomain"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_TransformationPlanMember" xlink:label="smhi_TransformationPlanMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RestructuringPlanAxis" xlink:label="us-gaap_RestructuringPlanAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SeveranceCosts1" xlink:label="us-gaap_SeveranceCosts1"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_StatementGeographicalAxis" xlink:label="srt_StatementGeographicalAxis"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_AfricaAndEuropeContinuingOperationsMember" xlink:label="smhi_AfricaAndEuropeContinuingOperationsMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OtherRestructuringCosts" xlink:label="us-gaap_OtherRestructuringCosts"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_MiddleEastAndAsiaMember" xlink:label="smhi_MiddleEastAndAsiaMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RestructuringCharges" xlink:label="us-gaap_RestructuringCharges"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_LatinAmericaMember" xlink:label="srt_LatinAmericaMember"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_RestructuringCostAndReserveLineItems" xlink:to="us-gaap_ScheduleOfRestructuringAndRelatedCostsTable" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_SegmentGeographicalDomain" xlink:to="country_US" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RestructuringPlanDomain" xlink:to="smhi_TransformationPlanMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_RestructuringPlanAxis" xlink:to="us-gaap_RestructuringPlanDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RestructuringCostAndReserveLineItems" xlink:to="us-gaap_SeveranceCosts1" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_StatementGeographicalAxis" xlink:to="srt_SegmentGeographicalDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfRestructuringAndRelatedCostsTable" xlink:to="us-gaap_RestructuringPlanAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_SegmentGeographicalDomain" xlink:to="smhi_AfricaAndEuropeContinuingOperationsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RestructuringCostAndReserveLineItems" xlink:to="us-gaap_OtherRestructuringCosts" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfRestructuringAndRelatedCostsTable" xlink:to="srt_StatementGeographicalAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_SegmentGeographicalDomain" xlink:to="smhi_MiddleEastAndAsiaMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RestructuringCostAndReserveLineItems" xlink:to="us-gaap_RestructuringCharges" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_SegmentGeographicalDomain" xlink:to="srt_LatinAmericaMember" priority="2" use="optional"/>
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureBusinessAcquisitionsAdditionalInformationDetails">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_BusinessAcquisitionLineItems" xlink:label="us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:label="us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="us-gaap_BusinessAcquisitionAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="us-gaap_BusinessAcquisitionAcquireeDomain_default"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_MergerAgreementMember" xlink:label="smhi_MergerAgreementMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_EquityMethodInvesteeNameDomain" xlink:label="srt_EquityMethodInvesteeNameDomain"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_OSVPartnersMember" xlink:label="smhi_OSVPartnersMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TypeOfArrangementAxis" xlink:label="us-gaap_TypeOfArrangementAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="us-gaap_ArrangementsAndNonarrangementTransactionsMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="us-gaap_ArrangementsAndNonarrangementTransactionsMember_default"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xlink:label="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PartnerTypeOfPartnersCapitalAccountAxis" xlink:label="us-gaap_PartnerTypeOfPartnersCapitalAccountAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PartnerTypeOfPartnersCapitalAccountNameDomain" xlink:label="us-gaap_PartnerTypeOfPartnersCapitalAccountNameDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PartnerTypeOfPartnersCapitalAccountNameDomain" xlink:label="us-gaap_PartnerTypeOfPartnersCapitalAccountNameDomain_default"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_MergerConsiderationMember" xlink:label="smhi_MergerConsiderationMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EquityInterestIssuedOrIssuableTypeDomain" xlink:label="us-gaap_EquityInterestIssuedOrIssuableTypeDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommonStockMember" xlink:label="us-gaap_CommonStockMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EquityInterestIssuedOrIssuableByTypeAxis" xlink:label="us-gaap_EquityInterestIssuedOrIssuableByTypeAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EquityInterestIssuedOrIssuableTypeDomain" xlink:label="us-gaap_EquityInterestIssuedOrIssuableTypeDomain_default"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued" xlink:label="us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:label="us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LimitedPartnerMember" xlink:label="us-gaap_LimitedPartnerMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_PlatformSupplyVesselsMember" xlink:label="smhi_PlatformSupplyVesselsMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_OsvPartnersMergerAgreementMember" xlink:label="smhi_OsvPartnersMergerAgreementMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_PaymentInKindPIKLoanMember" xlink:label="smhi_PaymentInKindPIKLoanMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_BusinessCombinationAssumedAndGuaranteeAmount" xlink:label="smhi_BusinessCombinationAssumedAndGuaranteeAmount"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_NumberOfVesselsOwned" xlink:label="smhi_NumberOfVesselsOwned"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired" xlink:label="us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_AverageAgeOfVessels" xlink:label="smhi_AverageAgeOfVessels"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_BusinessAcquisitionLineItems" xlink:to="us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_BusinessAcquisitionAxis" xlink:to="us-gaap_BusinessAcquisitionAcquireeDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_BusinessAcquisitionAxis" xlink:to="us-gaap_BusinessAcquisitionAcquireeDomain_default" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_BusinessAcquisitionAcquireeDomain" xlink:to="smhi_MergerAgreementMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_EquityMethodInvesteeNameDomain" xlink:to="smhi_OSVPartnersMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_TypeOfArrangementAxis" xlink:to="us-gaap_ArrangementsAndNonarrangementTransactionsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_TypeOfArrangementAxis" xlink:to="us-gaap_ArrangementsAndNonarrangementTransactionsMember_default" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:to="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_PartnerTypeOfPartnersCapitalAccountAxis" xlink:to="us-gaap_PartnerTypeOfPartnersCapitalAccountNameDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_PartnerTypeOfPartnersCapitalAccountAxis" xlink:to="us-gaap_PartnerTypeOfPartnersCapitalAccountNameDomain_default" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xlink:to="srt_EquityMethodInvesteeNameDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:to="smhi_MergerConsiderationMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityInterestIssuedOrIssuableTypeDomain" xlink:to="us-gaap_CommonStockMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_EquityInterestIssuedOrIssuableByTypeAxis" xlink:to="us-gaap_EquityInterestIssuedOrIssuableTypeDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_EquityInterestIssuedOrIssuableByTypeAxis" xlink:to="us-gaap_EquityInterestIssuedOrIssuableTypeDomain_default" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_BusinessAcquisitionLineItems" xlink:to="us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:to="us-gaap_PropertyPlantAndEquipmentTypeDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PartnerTypeOfPartnersCapitalAccountNameDomain" xlink:to="us-gaap_LimitedPartnerMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="smhi_PlatformSupplyVesselsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_BusinessAcquisitionAcquireeDomain" xlink:to="smhi_OsvPartnersMergerAgreementMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:to="us-gaap_BusinessAcquisitionAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:to="smhi_PaymentInKindPIKLoanMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_BusinessAcquisitionLineItems" xlink:to="smhi_BusinessCombinationAssumedAndGuaranteeAmount" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:to="us-gaap_EquityInterestIssuedOrIssuableByTypeAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_BusinessAcquisitionLineItems" xlink:to="smhi_NumberOfVesselsOwned" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:to="us-gaap_TypeOfArrangementAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_BusinessAcquisitionLineItems" xlink:to="us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:to="us-gaap_PartnerTypeOfPartnersCapitalAccountAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_BusinessAcquisitionLineItems" xlink:to="smhi_AverageAgeOfVessels" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="5" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:to="us-gaap_PropertyPlantAndEquipmentByTypeAxis" priority="2" use="optional"/>
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureBusinessAcquisitionsSummaryOfPurchasePriceAllocationOfAcquiredAssetsDetails">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfInvestmentsLineItems" xlink:label="us-gaap_ScheduleOfInvestmentsLineItems"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfInvestmentsTable" xlink:label="us-gaap_ScheduleOfInvestmentsTable"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_EquityMethodInvesteeNameDomain" xlink:label="srt_EquityMethodInvesteeNameDomain"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_OSVPartnersMember" xlink:label="smhi_OSVPartnersMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssets" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssets"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xlink:label="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentAssets" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentAssets"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilities" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilities"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesLongTermDebt" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesLongTermDebt"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNetCostBasisForPurchase" xlink:label="smhi_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNetCostBasisForPurchase"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPurchasePrice" xlink:label="smhi_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPurchasePrice"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAcquisitionCosts" xlink:label="smhi_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAcquisitionCosts"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EquityMethodInvestments" xlink:label="us-gaap_EquityMethodInvestments"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_ScheduleOfInvestmentsLineItems" xlink:to="us-gaap_ScheduleOfInvestmentsTable" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_EquityMethodInvesteeNameDomain" xlink:to="smhi_OSVPartnersMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScheduleOfInvestmentsLineItems" xlink:to="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssets" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xlink:to="srt_EquityMethodInvesteeNameDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfInvestmentsTable" xlink:to="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScheduleOfInvestmentsLineItems" xlink:to="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentAssets" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScheduleOfInvestmentsLineItems" xlink:to="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilities" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScheduleOfInvestmentsLineItems" xlink:to="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesLongTermDebt" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScheduleOfInvestmentsLineItems" xlink:to="smhi_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNetCostBasisForPurchase" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="5" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScheduleOfInvestmentsLineItems" xlink:to="smhi_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPurchasePrice" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="6" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScheduleOfInvestmentsLineItems" xlink:to="smhi_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAcquisitionCosts" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="7" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScheduleOfInvestmentsLineItems" xlink:to="us-gaap_EquityMethodInvestments" priority="2" use="optional"/>
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureNoteReceivableAdditionalInformationDetails">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AccountsNotesAndLoansReceivableLineItems" xlink:label="us-gaap_AccountsNotesAndLoansReceivableLineItems"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable" xlink:label="us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeAxis" xlink:label="srt_RangeAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeMember" xlink:label="srt_RangeMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_MinimumMember" xlink:label="srt_MinimumMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CreditFacilityDomain" xlink:label="us-gaap_CreditFacilityDomain"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_TermLoanMember" xlink:label="smhi_TermLoanMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CreditFacilityAxis" xlink:label="us-gaap_CreditFacilityAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CreditFacilityDomain" xlink:label="us-gaap_CreditFacilityDomain_default"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentAxis" xlink:label="us-gaap_DebtInstrumentAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="us-gaap_DebtInstrumentNameDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="us-gaap_DebtInstrumentNameDomain_default"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_MexMarOriginalFacilityAgreementMember" xlink:label="smhi_MexMarOriginalFacilityAgreementMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentFaceAmount" xlink:label="us-gaap_DebtInstrumentFaceAmount"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_MaximumMember" xlink:label="srt_MaximumMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_MexMarSecondAmendedAndRestatedFacilityAgreementMember" xlink:label="smhi_MexMarSecondAmendedAndRestatedFacilityAgreementMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PaymentsOfDebtExtinguishmentCosts" xlink:label="us-gaap_PaymentsOfDebtExtinguishmentCosts"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_MexMarThirdAmendedAndRestatedFacilityAgreementMember" xlink:label="smhi_MexMarThirdAmendedAndRestatedFacilityAgreementMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentMaturityDate" xlink:label="us-gaap_DebtInstrumentMaturityDate"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RestrictedCash" xlink:label="us-gaap_RestrictedCash"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentInterestRateEffectivePercentage" xlink:label="us-gaap_DebtInstrumentInterestRateEffectivePercentage"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentFrequencyOfPeriodicPayment" xlink:label="us-gaap_DebtInstrumentFrequencyOfPeriodicPayment"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentPeriodicPaymentPrincipal" xlink:label="us-gaap_DebtInstrumentPeriodicPaymentPrincipal"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_DebtInstrumentLoanAmountDue" xlink:label="smhi_DebtInstrumentLoanAmountDue"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_AccountsNotesAndLoansReceivableLineItems" xlink:to="us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_RangeAxis" xlink:to="srt_RangeMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_RangeMember" xlink:to="srt_MinimumMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_CreditFacilityDomain" xlink:to="smhi_TermLoanMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_CreditFacilityAxis" xlink:to="us-gaap_CreditFacilityDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_CreditFacilityAxis" xlink:to="us-gaap_CreditFacilityDomain_default" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable" xlink:to="srt_RangeAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_DebtInstrumentAxis" xlink:to="us-gaap_DebtInstrumentNameDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_DebtInstrumentAxis" xlink:to="us-gaap_DebtInstrumentNameDomain_default" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="smhi_MexMarOriginalFacilityAgreementMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccountsNotesAndLoansReceivableLineItems" xlink:to="us-gaap_DebtInstrumentFaceAmount" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_RangeMember" xlink:to="srt_MaximumMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable" xlink:to="us-gaap_DebtInstrumentAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="smhi_MexMarSecondAmendedAndRestatedFacilityAgreementMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccountsNotesAndLoansReceivableLineItems" xlink:to="us-gaap_PaymentsOfDebtExtinguishmentCosts" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable" xlink:to="us-gaap_CreditFacilityAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="smhi_MexMarThirdAmendedAndRestatedFacilityAgreementMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccountsNotesAndLoansReceivableLineItems" xlink:to="us-gaap_DebtInstrumentMaturityDate" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccountsNotesAndLoansReceivableLineItems" xlink:to="us-gaap_RestrictedCash" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccountsNotesAndLoansReceivableLineItems" xlink:to="us-gaap_DebtInstrumentInterestRateEffectivePercentage" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="5" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccountsNotesAndLoansReceivableLineItems" xlink:to="us-gaap_DebtInstrumentFrequencyOfPeriodicPayment" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="6" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccountsNotesAndLoansReceivableLineItems" xlink:to="us-gaap_DebtInstrumentPeriodicPaymentPrincipal" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="7" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AccountsNotesAndLoansReceivableLineItems" xlink:to="smhi_DebtInstrumentLoanAmountDue" priority="2" use="optional"/>
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureEquipmentAcquisitionsAndDispositionsAdditionalInformationDetails">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentLineItems" xlink:label="us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:label="us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="us-gaap_BusinessAcquisitionAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_SEACORMarlinLLCMember" xlink:label="smhi_SEACORMarlinLLCMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_EquityMethodInvesteeNameDomain" xlink:label="srt_EquityMethodInvesteeNameDomain"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_EquityInvestmentsIn50OrLessOwnedCompaniesMember" xlink:label="smhi_EquityInvestmentsIn50OrLessOwnedCompaniesMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_CapitalExpendituresAndPaymentsOnEquipment" xlink:label="smhi_CapitalExpendituresAndPaymentsOnEquipment"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeAxis" xlink:label="srt_RangeAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeMember" xlink:label="srt_RangeMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_MaximumMember" xlink:label="srt_MaximumMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xlink:label="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentAxis" xlink:label="us-gaap_DebtInstrumentAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="us-gaap_DebtInstrumentNameDomain"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_FalconGlobalUSATermLoanFacilityMember" xlink:label="smhi_FalconGlobalUSATermLoanFacilityMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:label="us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_CrewTransferVesselsMember" xlink:label="smhi_CrewTransferVesselsMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SaleOfStockPercentageOfOwnershipAfterTransaction" xlink:label="us-gaap_SaleOfStockPercentageOfOwnershipAfterTransaction"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_WindcatWorkboatsMember" xlink:label="smhi_WindcatWorkboatsMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired" xlink:label="us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_VesselUnderConstructionMember" xlink:label="smhi_VesselUnderConstructionMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EquityMethodInvestmentAggregateCost" xlink:label="us-gaap_EquityMethodInvestmentAggregateCost"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_VesselUnderConstructionAndOtherEquipmentMember" xlink:label="smhi_VesselUnderConstructionAndOtherEquipmentMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ProceedsFromIssuanceOfCommonStock" xlink:label="us-gaap_ProceedsFromIssuanceOfCommonStock"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_AnchorHandlingTowingSupplyVesselMember" xlink:label="smhi_AnchorHandlingTowingSupplyVesselMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LineOfCreditFacilityMaximumAmountOutstandingDuringPeriod" xlink:label="us-gaap_LineOfCreditFacilityMaximumAmountOutstandingDuringPeriod"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_SpecialtyVesselMember" xlink:label="smhi_SpecialtyVesselMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_NumberOfEquipmentAcquired" xlink:label="smhi_NumberOfEquipmentAcquired"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_FastSupportVesselsMember" xlink:label="smhi_FastSupportVesselsMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_NumberOfAdditionalJointVenturesHeldInterests" xlink:label="smhi_NumberOfAdditionalJointVenturesHeldInterests"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_PlatformSupplyVesselsMember" xlink:label="smhi_PlatformSupplyVesselsMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_GainLossOnSaleOfPropertyPlantEquipment" xlink:label="us-gaap_GainLossOnSaleOfPropertyPlantEquipment"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_PlatformSupplyVesselsAndFastSupportVesselsMember" xlink:label="smhi_PlatformSupplyVesselsAndFastSupportVesselsMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_ProceedsFromPropertyPlantAndEquipmentIncludingDepositsAndGainOnSale" xlink:label="smhi_ProceedsFromPropertyPlantAndEquipmentIncludingDepositsAndGainOnSale"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_VesselsMember" xlink:label="smhi_VesselsMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_NumberOfEquipmentSold" xlink:label="smhi_NumberOfEquipmentSold"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_LiftboatsMember" xlink:label="smhi_LiftboatsMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ProceedsFromSaleOfPropertyPlantAndEquipment" xlink:label="us-gaap_ProceedsFromSaleOfPropertyPlantAndEquipment"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_ProceedsFromDeposits" xlink:label="smhi_ProceedsFromDeposits"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_ReducedOfDebtUnderCreditFacility" xlink:label="smhi_ReducedOfDebtUnderCreditFacility"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_PropertyPlantEquipmentConsiderationTransferred" xlink:label="smhi_PropertyPlantEquipmentConsiderationTransferred"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EquityMethodInvestmentOwnershipPercentage" xlink:label="us-gaap_EquityMethodInvestmentOwnershipPercentage"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ImpairmentOfLongLivedAssetsToBeDisposedOf" xlink:label="us-gaap_ImpairmentOfLongLivedAssetsToBeDisposedOf"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_BusinessAcquisitionAxis" xlink:to="us-gaap_BusinessAcquisitionAcquireeDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_BusinessAcquisitionAcquireeDomain" xlink:to="smhi_SEACORMarlinLLCMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_EquityMethodInvesteeNameDomain" xlink:to="smhi_EquityInvestmentsIn50OrLessOwnedCompaniesMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="smhi_CapitalExpendituresAndPaymentsOnEquipment" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_RangeAxis" xlink:to="srt_RangeMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_RangeMember" xlink:to="srt_MaximumMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xlink:to="srt_EquityMethodInvesteeNameDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_DebtInstrumentAxis" xlink:to="us-gaap_DebtInstrumentNameDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:to="srt_RangeAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="smhi_FalconGlobalUSATermLoanFacilityMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:to="us-gaap_PropertyPlantAndEquipmentTypeDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="smhi_CrewTransferVesselsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="us-gaap_SaleOfStockPercentageOfOwnershipAfterTransaction" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:to="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="smhi_WindcatWorkboatsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:to="us-gaap_BusinessAcquisitionAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="smhi_VesselUnderConstructionMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="us-gaap_EquityMethodInvestmentAggregateCost" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:to="us-gaap_PropertyPlantAndEquipmentByTypeAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="smhi_VesselUnderConstructionAndOtherEquipmentMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="us-gaap_ProceedsFromIssuanceOfCommonStock" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:to="us-gaap_DebtInstrumentAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="smhi_AnchorHandlingTowingSupplyVesselMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="5" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="us-gaap_LineOfCreditFacilityMaximumAmountOutstandingDuringPeriod" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="5" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="smhi_SpecialtyVesselMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="6" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="smhi_NumberOfEquipmentAcquired" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="6" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="smhi_FastSupportVesselsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="7" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="smhi_NumberOfAdditionalJointVenturesHeldInterests" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="7" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="smhi_PlatformSupplyVesselsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="8" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="us-gaap_GainLossOnSaleOfPropertyPlantEquipment" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="8" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="smhi_PlatformSupplyVesselsAndFastSupportVesselsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="9" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="smhi_ProceedsFromPropertyPlantAndEquipmentIncludingDepositsAndGainOnSale" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="9" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="smhi_VesselsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="10" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="smhi_NumberOfEquipmentSold" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="10" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="smhi_LiftboatsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="11" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="us-gaap_ProceedsFromSaleOfPropertyPlantAndEquipment" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="12" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="smhi_ProceedsFromDeposits" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="13" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="smhi_ReducedOfDebtUnderCreditFacility" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="14" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="smhi_PropertyPlantEquipmentConsiderationTransferred" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="15" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="us-gaap_EquityMethodInvestmentOwnershipPercentage" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="17" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="us-gaap_ImpairmentOfLongLivedAssetsToBeDisposedOf" priority="2" use="optional"/>
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureEquipmentAcquisitionsAndDispositionsScheduleOfVesselAcquiredAndDisposedDetails">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentLineItems" xlink:label="us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:label="us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_NumberOfEquipmentAcquired" xlink:label="smhi_NumberOfEquipmentAcquired"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:label="us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_AnchorHandlingTowingSupplyVesselMember" xlink:label="smhi_AnchorHandlingTowingSupplyVesselMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_NumberOfEquipmentRemovedFromService" xlink:label="smhi_NumberOfEquipmentRemovedFromService"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_FastSupportVesselsMember" xlink:label="smhi_FastSupportVesselsMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_PlatformSupplyVesselsMember" xlink:label="smhi_PlatformSupplyVesselsMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_OffshoreSupportVesselsLiftboatsMember" xlink:label="smhi_OffshoreSupportVesselsLiftboatsMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_SpecialtyVesselMember" xlink:label="smhi_SpecialtyVesselMember"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="smhi_NumberOfEquipmentAcquired" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:to="us-gaap_PropertyPlantAndEquipmentByTypeAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:to="us-gaap_PropertyPlantAndEquipmentTypeDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="smhi_AnchorHandlingTowingSupplyVesselMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="smhi_NumberOfEquipmentRemovedFromService" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="smhi_FastSupportVesselsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="smhi_PlatformSupplyVesselsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="smhi_OffshoreSupportVesselsLiftboatsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="smhi_SpecialtyVesselMember" priority="2" use="optional"/>
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureEquipmentAcquisitionsAndDispositionsScheduleOfVesselAcquiredAndDisposedParentheticalDetails">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentLineItems" xlink:label="us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:label="us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_NumberOfEquipmentAcquiredExcludedFromDeliveriesOfOffshoreSupportVessels" xlink:label="smhi_NumberOfEquipmentAcquiredExcludedFromDeliveriesOfOffshoreSupportVessels"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:label="us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_PlatformSupplyVesselsMember" xlink:label="smhi_PlatformSupplyVesselsMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_NumberOfEquipmentHeldForSaleExcludedFromDeliveriesOfOffshoreSupportVessels" xlink:label="smhi_NumberOfEquipmentHeldForSaleExcludedFromDeliveriesOfOffshoreSupportVessels"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_CrewTransferVesselsMember" xlink:label="smhi_CrewTransferVesselsMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_NumberOfEquipmentRemovedFromServiceExcludesFromMajorEquipmentDispositions" xlink:label="smhi_NumberOfEquipmentRemovedFromServiceExcludesFromMajorEquipmentDispositions"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_OffshoreSupportVesselsLiftboatsMember" xlink:label="smhi_OffshoreSupportVesselsLiftboatsMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_NumberOfEquipmentHeldForSaleExcludedFromMajorEquipmentDispositions" xlink:label="smhi_NumberOfEquipmentHeldForSaleExcludedFromMajorEquipmentDispositions"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_AnchorHandlingTowingSupplyVesselMember" xlink:label="smhi_AnchorHandlingTowingSupplyVesselMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_SpecialtyVesselMember" xlink:label="smhi_SpecialtyVesselMember"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="smhi_NumberOfEquipmentAcquiredExcludedFromDeliveriesOfOffshoreSupportVessels" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:to="us-gaap_PropertyPlantAndEquipmentByTypeAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:to="us-gaap_PropertyPlantAndEquipmentTypeDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="smhi_PlatformSupplyVesselsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="smhi_NumberOfEquipmentHeldForSaleExcludedFromDeliveriesOfOffshoreSupportVessels" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="smhi_CrewTransferVesselsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="smhi_NumberOfEquipmentRemovedFromServiceExcludesFromMajorEquipmentDispositions" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="smhi_OffshoreSupportVesselsLiftboatsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="smhi_NumberOfEquipmentHeldForSaleExcludedFromMajorEquipmentDispositions" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="smhi_AnchorHandlingTowingSupplyVesselMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="smhi_SpecialtyVesselMember" priority="2" use="optional"/>
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureEquipmentAcquisitionsAndDispositionsScheduleOfGainOnSaleOfWindcatWorkboatsDetails">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentLineItems" xlink:label="us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:label="us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_ProceedsFromSaleOfPropertyPlantAndEquipmentGross" xlink:label="smhi_ProceedsFromSaleOfPropertyPlantAndEquipmentGross"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:label="us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_WindcatWorkboatsMember" xlink:label="smhi_WindcatWorkboatsMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_PaymentsForTransactionsFeesAndOtherCosts" xlink:label="smhi_PaymentsForTransactionsFeesAndOtherCosts"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_CashSoldOnPropertyPlantAndEquipmentDisposal" xlink:label="smhi_CashSoldOnPropertyPlantAndEquipmentDisposal"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ProceedsFromSaleOfPropertyPlantAndEquipment" xlink:label="us-gaap_ProceedsFromSaleOfPropertyPlantAndEquipment"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentDisposals" xlink:label="us-gaap_PropertyPlantAndEquipmentDisposals"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentTransfersAndChanges" xlink:label="us-gaap_PropertyPlantAndEquipmentTransfersAndChanges"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_GainLossOnSaleOfPropertyPlantEquipment" xlink:label="us-gaap_GainLossOnSaleOfPropertyPlantEquipment"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="smhi_ProceedsFromSaleOfPropertyPlantAndEquipmentGross" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:to="us-gaap_PropertyPlantAndEquipmentByTypeAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:to="us-gaap_PropertyPlantAndEquipmentTypeDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="smhi_WindcatWorkboatsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="smhi_PaymentsForTransactionsFeesAndOtherCosts" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="smhi_CashSoldOnPropertyPlantAndEquipmentDisposal" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="us-gaap_ProceedsFromSaleOfPropertyPlantAndEquipment" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="us-gaap_PropertyPlantAndEquipmentDisposals" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="5" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="us-gaap_PropertyPlantAndEquipmentTransfersAndChanges" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="6" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="us-gaap_GainLossOnSaleOfPropertyPlantEquipment" priority="2" use="optional"/>
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureInvestmentsAtEquityAndAdvancesTo50OrLessOwnedCompaniesScheduleOfEquityInvestmentsDetails">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfInvestmentsLineItems" xlink:label="us-gaap_ScheduleOfInvestmentsLineItems"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfInvestmentsTable" xlink:label="us-gaap_ScheduleOfInvestmentsTable"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_EquityMethodInvesteeNameDomain" xlink:label="srt_EquityMethodInvesteeNameDomain"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_MexMarMember" xlink:label="smhi_MexMarMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeAxis" xlink:label="srt_RangeAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeMember" xlink:label="srt_RangeMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_MinimumMember" xlink:label="srt_MinimumMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EquityMethodInvestmentOwnershipPercentage" xlink:label="us-gaap_EquityMethodInvestmentOwnershipPercentage"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xlink:label="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EquityMethodInvestmentNonconsolidatedInvesteeAxis" xlink:label="us-gaap_EquityMethodInvestmentNonconsolidatedInvesteeAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EquityMethodInvestmentNonconsolidatedInvesteeDomain" xlink:label="us-gaap_EquityMethodInvestmentNonconsolidatedInvesteeDomain"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_AllOtherExcludingMexMarFalconGlobalSeaCatCrewzerAndSeaCatCrewzerIIMember" xlink:label="smhi_AllOtherExcludingMexMarFalconGlobalSeaCatCrewzerAndSeaCatCrewzerIIMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EquityMethodInvestmentNonconsolidatedInvesteeDomain" xlink:label="us-gaap_EquityMethodInvestmentNonconsolidatedInvesteeDomain_default"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_SEACORMarlinLLCMember" xlink:label="smhi_SEACORMarlinLLCMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_MaximumMember" xlink:label="srt_MaximumMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EquityMethodInvestments" xlink:label="us-gaap_EquityMethodInvestments"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_OffshoreVesselHoldingsMember" xlink:label="smhi_OffshoreVesselHoldingsMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AssetsCurrent" xlink:label="us-gaap_AssetsCurrent"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_SeabulkAngolaMember" xlink:label="smhi_SeabulkAngolaMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AssetsNoncurrent" xlink:label="us-gaap_AssetsNoncurrent"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_SeacorMarineArabiaMember" xlink:label="smhi_SeacorMarineArabiaMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LiabilitiesCurrent" xlink:label="us-gaap_LiabilitiesCurrent"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_OtherOffshoreMarineServicesJointVenturesMember" xlink:label="smhi_OtherOffshoreMarineServicesJointVenturesMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LiabilitiesNoncurrent" xlink:label="us-gaap_LiabilitiesNoncurrent"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RevenueFromContractWithCustomerIncludingAssessedTax" xlink:label="us-gaap_RevenueFromContractWithCustomerIncludingAssessedTax"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_EquityMethodInvestmentSummarizedFinancialInformationOperatingAndAdministrative" xlink:label="smhi_EquityMethodInvestmentSummarizedFinancialInformationOperatingAndAdministrative"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_EquityMethodInvestmentSummarizedFinancialInformationDepreciation" xlink:label="smhi_EquityMethodInvestmentSummarizedFinancialInformationDepreciation"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_EquityMethodInvestmentSummarizedFinancialInformationOperatingCostsAndExpenses" xlink:label="smhi_EquityMethodInvestmentSummarizedFinancialInformationOperatingCostsAndExpenses"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_EquityMethodInvestmentSummarizedFinancialInformationIncomeLossOnAssetDispositionsAndImpairmentsNet" xlink:label="smhi_EquityMethodInvestmentSummarizedFinancialInformationIncomeLossOnAssetDispositionsAndImpairmentsNet"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest" xlink:label="us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ProfitLoss" xlink:label="us-gaap_ProfitLoss"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_ScheduleOfInvestmentsLineItems" xlink:to="us-gaap_ScheduleOfInvestmentsTable" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_EquityMethodInvesteeNameDomain" xlink:to="smhi_MexMarMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_RangeAxis" xlink:to="srt_RangeMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_RangeMember" xlink:to="srt_MinimumMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScheduleOfInvestmentsLineItems" xlink:to="us-gaap_EquityMethodInvestmentOwnershipPercentage" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xlink:to="srt_EquityMethodInvesteeNameDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfInvestmentsTable" xlink:to="us-gaap_EquityMethodInvestmentNonconsolidatedInvesteeAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityMethodInvestmentNonconsolidatedInvesteeDomain" xlink:to="smhi_AllOtherExcludingMexMarFalconGlobalSeaCatCrewzerAndSeaCatCrewzerIIMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_EquityMethodInvestmentNonconsolidatedInvesteeAxis" xlink:to="us-gaap_EquityMethodInvestmentNonconsolidatedInvesteeDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_EquityMethodInvestmentNonconsolidatedInvesteeAxis" xlink:to="us-gaap_EquityMethodInvestmentNonconsolidatedInvesteeDomain_default" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_EquityMethodInvesteeNameDomain" xlink:to="smhi_SEACORMarlinLLCMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_RangeMember" xlink:to="srt_MaximumMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScheduleOfInvestmentsLineItems" xlink:to="us-gaap_EquityMethodInvestments" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfInvestmentsTable" xlink:to="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_EquityMethodInvesteeNameDomain" xlink:to="smhi_OffshoreVesselHoldingsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScheduleOfInvestmentsLineItems" xlink:to="us-gaap_AssetsCurrent" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfInvestmentsTable" xlink:to="srt_RangeAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_EquityMethodInvesteeNameDomain" xlink:to="smhi_SeabulkAngolaMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScheduleOfInvestmentsLineItems" xlink:to="us-gaap_AssetsNoncurrent" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_EquityMethodInvesteeNameDomain" xlink:to="smhi_SeacorMarineArabiaMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScheduleOfInvestmentsLineItems" xlink:to="us-gaap_LiabilitiesCurrent" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="5" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_EquityMethodInvesteeNameDomain" xlink:to="smhi_OtherOffshoreMarineServicesJointVenturesMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="5" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScheduleOfInvestmentsLineItems" xlink:to="us-gaap_LiabilitiesNoncurrent" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="6" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScheduleOfInvestmentsLineItems" xlink:to="us-gaap_RevenueFromContractWithCustomerIncludingAssessedTax" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="7" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScheduleOfInvestmentsLineItems" xlink:to="smhi_EquityMethodInvestmentSummarizedFinancialInformationOperatingAndAdministrative" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="8" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScheduleOfInvestmentsLineItems" xlink:to="smhi_EquityMethodInvestmentSummarizedFinancialInformationDepreciation" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="9" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScheduleOfInvestmentsLineItems" xlink:to="smhi_EquityMethodInvestmentSummarizedFinancialInformationOperatingCostsAndExpenses" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="10" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScheduleOfInvestmentsLineItems" xlink:to="smhi_EquityMethodInvestmentSummarizedFinancialInformationIncomeLossOnAssetDispositionsAndImpairmentsNet" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="11" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScheduleOfInvestmentsLineItems" xlink:to="us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="12" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScheduleOfInvestmentsLineItems" xlink:to="us-gaap_ProfitLoss" priority="2" use="optional"/>
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureInvestmentsAtEquityAndAdvancesTo50OrLessOwnedCompaniesAdditionalInformationDetails">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfInvestmentsLineItems" xlink:label="us-gaap_ScheduleOfInvestmentsLineItems"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfInvestmentsTable" xlink:label="us-gaap_ScheduleOfInvestmentsTable"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_EquityMethodInvesteeNameDomain" xlink:label="srt_EquityMethodInvesteeNameDomain"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_MexMarMember" xlink:label="smhi_MexMarMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeAxis" xlink:label="srt_RangeAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeMember" xlink:label="srt_RangeMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_MaximumMember" xlink:label="srt_MaximumMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_EquityMethodInvestmentsUnrealizedIntercompanyProfitLossNotEliminatedAmount" xlink:label="smhi_EquityMethodInvestmentsUnrealizedIntercompanyProfitLossNotEliminatedAmount"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TransactionTypeAxis" xlink:label="us-gaap_TransactionTypeAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TransactionDomain" xlink:label="us-gaap_TransactionDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TransactionDomain" xlink:label="us-gaap_TransactionDomain_default"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_PriorToClosingOfFrameworkAgreementMember" xlink:label="smhi_PriorToClosingOfFrameworkAgreementMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xlink:label="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_OwnershipDomain" xlink:label="srt_OwnershipDomain"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_OTMMember" xlink:label="smhi_OTMMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:label="us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_UPOffshoresMember" xlink:label="smhi_UPOffshoresMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_OwnershipAxis" xlink:label="srt_OwnershipAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_OwnershipDomain" xlink:label="srt_OwnershipDomain_default"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_OffshoreSupportVesselsMember" xlink:label="smhi_OffshoreSupportVesselsMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_SEACORMarlinLLCMember" xlink:label="smhi_SEACORMarlinLLCMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_MinimumMember" xlink:label="srt_MinimumMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_NumberOfEquipmentOperated" xlink:label="smhi_NumberOfEquipmentOperated"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_SubsidiariesOfCMEMember" xlink:label="smhi_SubsidiariesOfCMEMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_OffshoreSupportVesselsSupplyMember" xlink:label="smhi_OffshoreSupportVesselsSupplyMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_SeacorMarineArabiaLlcAndOtherMember" xlink:label="smhi_SeacorMarineArabiaLlcAndOtherMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ProceedsFromEquityMethodInvestmentDividendsOrDistributionsReturnOfCapital" xlink:label="us-gaap_ProceedsFromEquityMethodInvestmentDividendsOrDistributionsReturnOfCapital"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_SubsidiariesOfOVHMember" xlink:label="smhi_SubsidiariesOfOVHMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_JackUpDrillingsMember" xlink:label="smhi_JackUpDrillingsMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_MexmarOffshoreInternationalMember" xlink:label="smhi_MexmarOffshoreInternationalMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RevenueFromRelatedParties" xlink:label="us-gaap_RevenueFromRelatedParties"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_FSVOffshoreSupportVesselsMember" xlink:label="smhi_FSVOffshoreSupportVesselsMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_MEXMAROffshoreMember" xlink:label="smhi_MEXMAROffshoreMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_EquityMethodInvestmentOwnershipPercentSold" xlink:label="smhi_EquityMethodInvestmentOwnershipPercentSold"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_OffshoreVesselHoldingsMember" xlink:label="smhi_OffshoreVesselHoldingsMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ProceedsFromDivestitureOfInterestInJointVenture" xlink:label="us-gaap_ProceedsFromDivestitureOfInterestInJointVenture"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_OffshoreVesselHoldingsAndOperadoraProductoraYExploradoraMexicanaSADeCVMember" xlink:label="smhi_OffshoreVesselHoldingsAndOperadoraProductoraYExploradoraMexicanaSADeCVMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_GainLossOnSaleOfBusiness" xlink:label="us-gaap_GainLossOnSaleOfBusiness"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EquityMethodInvestmentOwnershipPercentage" xlink:label="us-gaap_EquityMethodInvestmentOwnershipPercentage"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners" xlink:label="us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_NumberOfVesselSold" xlink:label="smhi_NumberOfVesselSold"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EquityMethodInvestmentSoldCarryingAmount" xlink:label="us-gaap_EquityMethodInvestmentSoldCarryingAmount"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_PercentageOfGainFromEquityEarnings" xlink:label="smhi_PercentageOfGainFromEquityEarnings"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EquityMethodInvestmentRealizedGainLossOnDisposal" xlink:label="us-gaap_EquityMethodInvestmentRealizedGainLossOnDisposal"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EquityMethodInvestmentDividendsOrDistributions" xlink:label="us-gaap_EquityMethodInvestmentDividendsOrDistributions"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EquityMethodInvestmentAggregateCost" xlink:label="us-gaap_EquityMethodInvestmentAggregateCost"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_NumberOfVesselsOwned" xlink:label="smhi_NumberOfVesselsOwned"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_NumberOfVesselsJointVentured" xlink:label="smhi_NumberOfVesselsJointVentured"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_EquityMethodInvestmentOwnershipPercentageTransferred" xlink:label="smhi_EquityMethodInvestmentOwnershipPercentageTransferred"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_EquityInterestTransferredConsiderationAndTransactionFee" xlink:label="smhi_EquityInterestTransferredConsiderationAndTransactionFee"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_MinorityInterestOwnershipPercentageByParent" xlink:label="us-gaap_MinorityInterestOwnershipPercentageByParent"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PaymentsToAcquireInterestInJointVenture" xlink:label="us-gaap_PaymentsToAcquireInterestInJointVenture"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PartnersCapitalAccountContributions" xlink:label="us-gaap_PartnersCapitalAccountContributions"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_FinancingAgreement" xlink:label="smhi_FinancingAgreement"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RepaymentsOfDebt" xlink:label="us-gaap_RepaymentsOfDebt"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EarlyRepaymentOfSeniorDebt" xlink:label="us-gaap_EarlyRepaymentOfSeniorDebt"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_DebtInstrumentForgivenessOfAccruedInterest" xlink:label="smhi_DebtInstrumentForgivenessOfAccruedInterest"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PaymentForManagementFee" xlink:label="us-gaap_PaymentForManagementFee"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_ReturnOfCapitalEquityMethodInvestment" xlink:label="smhi_ReturnOfCapitalEquityMethodInvestment"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ProceedsFromSaleOfEquityMethodInvestments" xlink:label="us-gaap_ProceedsFromSaleOfEquityMethodInvestments"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_GainLossOnSaleOfEquityInvestments" xlink:label="us-gaap_GainLossOnSaleOfEquityInvestments"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_ScheduleOfInvestmentsLineItems" xlink:to="us-gaap_ScheduleOfInvestmentsTable" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_EquityMethodInvesteeNameDomain" xlink:to="smhi_MexMarMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_RangeAxis" xlink:to="srt_RangeMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_RangeMember" xlink:to="srt_MaximumMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScheduleOfInvestmentsLineItems" xlink:to="smhi_EquityMethodInvestmentsUnrealizedIntercompanyProfitLossNotEliminatedAmount" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_TransactionTypeAxis" xlink:to="us-gaap_TransactionDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_TransactionTypeAxis" xlink:to="us-gaap_TransactionDomain_default" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_TransactionDomain" xlink:to="smhi_PriorToClosingOfFrameworkAgreementMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xlink:to="srt_EquityMethodInvesteeNameDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_OwnershipDomain" xlink:to="smhi_OTMMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfInvestmentsTable" xlink:to="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:to="us-gaap_PropertyPlantAndEquipmentTypeDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_EntityDomain" xlink:to="smhi_UPOffshoresMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_OwnershipAxis" xlink:to="srt_OwnershipDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="srt_OwnershipAxis" xlink:to="srt_OwnershipDomain_default" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="smhi_OffshoreSupportVesselsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_EquityMethodInvesteeNameDomain" xlink:to="smhi_SEACORMarlinLLCMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_RangeMember" xlink:to="srt_MinimumMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScheduleOfInvestmentsLineItems" xlink:to="smhi_NumberOfEquipmentOperated" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_OwnershipDomain" xlink:to="smhi_SubsidiariesOfCMEMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfInvestmentsTable" xlink:to="us-gaap_PropertyPlantAndEquipmentByTypeAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="smhi_OffshoreSupportVesselsSupplyMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_EquityMethodInvesteeNameDomain" xlink:to="smhi_SeacorMarineArabiaLlcAndOtherMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScheduleOfInvestmentsLineItems" xlink:to="us-gaap_ProceedsFromEquityMethodInvestmentDividendsOrDistributionsReturnOfCapital" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_OwnershipDomain" xlink:to="smhi_SubsidiariesOfOVHMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfInvestmentsTable" xlink:to="us-gaap_TransactionTypeAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="smhi_JackUpDrillingsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_EquityMethodInvesteeNameDomain" xlink:to="smhi_MexmarOffshoreInternationalMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScheduleOfInvestmentsLineItems" xlink:to="us-gaap_RevenueFromRelatedParties" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfInvestmentsTable" xlink:to="dei_LegalEntityAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="smhi_FSVOffshoreSupportVesselsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_EquityMethodInvesteeNameDomain" xlink:to="smhi_MEXMAROffshoreMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScheduleOfInvestmentsLineItems" xlink:to="smhi_EquityMethodInvestmentOwnershipPercentSold" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfInvestmentsTable" xlink:to="srt_RangeAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="5" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_EquityMethodInvesteeNameDomain" xlink:to="smhi_OffshoreVesselHoldingsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="5" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScheduleOfInvestmentsLineItems" xlink:to="us-gaap_ProceedsFromDivestitureOfInterestInJointVenture" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="5" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfInvestmentsTable" xlink:to="srt_OwnershipAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="6" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_EquityMethodInvesteeNameDomain" xlink:to="smhi_OffshoreVesselHoldingsAndOperadoraProductoraYExploradoraMexicanaSADeCVMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="6" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScheduleOfInvestmentsLineItems" xlink:to="us-gaap_GainLossOnSaleOfBusiness" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="7" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScheduleOfInvestmentsLineItems" xlink:to="us-gaap_EquityMethodInvestmentOwnershipPercentage" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="8" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScheduleOfInvestmentsLineItems" xlink:to="us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="9" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScheduleOfInvestmentsLineItems" xlink:to="smhi_NumberOfVesselSold" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="10" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScheduleOfInvestmentsLineItems" xlink:to="us-gaap_EquityMethodInvestmentSoldCarryingAmount" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="11" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScheduleOfInvestmentsLineItems" xlink:to="smhi_PercentageOfGainFromEquityEarnings" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="12" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScheduleOfInvestmentsLineItems" xlink:to="us-gaap_EquityMethodInvestmentRealizedGainLossOnDisposal" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="13" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScheduleOfInvestmentsLineItems" xlink:to="us-gaap_EquityMethodInvestmentDividendsOrDistributions" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="14" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScheduleOfInvestmentsLineItems" xlink:to="us-gaap_EquityMethodInvestmentAggregateCost" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="15" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScheduleOfInvestmentsLineItems" xlink:to="smhi_NumberOfVesselsOwned" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="16" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScheduleOfInvestmentsLineItems" xlink:to="smhi_NumberOfVesselsJointVentured" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="17" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScheduleOfInvestmentsLineItems" xlink:to="smhi_EquityMethodInvestmentOwnershipPercentageTransferred" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="18" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScheduleOfInvestmentsLineItems" xlink:to="smhi_EquityInterestTransferredConsiderationAndTransactionFee" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="19" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScheduleOfInvestmentsLineItems" xlink:to="us-gaap_MinorityInterestOwnershipPercentageByParent" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="20" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScheduleOfInvestmentsLineItems" xlink:to="us-gaap_PaymentsToAcquireInterestInJointVenture" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="21" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScheduleOfInvestmentsLineItems" xlink:to="us-gaap_PartnersCapitalAccountContributions" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="22" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScheduleOfInvestmentsLineItems" xlink:to="smhi_FinancingAgreement" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="23" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScheduleOfInvestmentsLineItems" xlink:to="us-gaap_RepaymentsOfDebt" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="24" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScheduleOfInvestmentsLineItems" xlink:to="us-gaap_EarlyRepaymentOfSeniorDebt" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="25" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScheduleOfInvestmentsLineItems" xlink:to="smhi_DebtInstrumentForgivenessOfAccruedInterest" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="26" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScheduleOfInvestmentsLineItems" xlink:to="us-gaap_PaymentForManagementFee" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="27" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScheduleOfInvestmentsLineItems" xlink:to="smhi_ReturnOfCapitalEquityMethodInvestment" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="28" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScheduleOfInvestmentsLineItems" xlink:to="us-gaap_ProceedsFromSaleOfEquityMethodInvestments" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="29" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScheduleOfInvestmentsLineItems" xlink:to="us-gaap_GainLossOnSaleOfEquityInvestments" priority="2" use="optional"/>
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureLeasesAdditionalInformationDetails">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LesseeLeaseDescriptionLineItems" xlink:label="us-gaap_LesseeLeaseDescriptionLineItems"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LesseeLeaseDescriptionTable" xlink:label="us-gaap_LesseeLeaseDescriptionTable"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_CumulativeEffectPeriodOfAdoptionAxis" xlink:label="srt_CumulativeEffectPeriodOfAdoptionAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_CumulativeEffectPeriodOfAdoptionDomain" xlink:label="srt_CumulativeEffectPeriodOfAdoptionDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeAxis" xlink:label="srt_RangeAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeMember" xlink:label="srt_RangeMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_MinimumMember" xlink:label="srt_MinimumMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OperatingLeaseRightOfUseAsset" xlink:label="us-gaap_OperatingLeaseRightOfUseAsset"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember" xlink:label="srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TypeOfAdoptionMember" xlink:label="us-gaap_TypeOfAdoptionMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AccountingStandardsUpdate201602Member" xlink:label="us-gaap_AccountingStandardsUpdate201602Member"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" xlink:label="us-gaap_AdjustmentsForNewAccountingPronouncementsAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis" xlink:label="us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ChangeInAccountingPrincipleMember" xlink:label="us-gaap_ChangeInAccountingPrincipleMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:label="us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_ChangeInAccountingPrincipleForEquipmentOfficeAndLandLeasesMember" xlink:label="smhi_ChangeInAccountingPrincipleForEquipmentOfficeAndLandLeasesMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_AnchorHandlingTowingSupplyVesselMember" xlink:label="smhi_AnchorHandlingTowingSupplyVesselMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_MaximumMember" xlink:label="srt_MaximumMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OperatingLeaseLiability" xlink:label="us-gaap_OperatingLeaseLiability"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_ChangeInAccountingPrincipleForUnamortizedDeferredGainsMember" xlink:label="smhi_ChangeInAccountingPrincipleForUnamortizedDeferredGainsMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_LiftboatsMember" xlink:label="smhi_LiftboatsMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RetainedEarningsAccumulatedDeficit" xlink:label="us-gaap_RetainedEarningsAccumulatedDeficit"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_FastSupportVesselsMember" xlink:label="smhi_FastSupportVesselsMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_CumulativeEffectOnRetainedEarningsBeforeTax" xlink:label="smhi_CumulativeEffectOnRetainedEarningsBeforeTax"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_VesselsMember" xlink:label="smhi_VesselsMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_CumulativeEffectOnRetainedEarningsTax" xlink:label="smhi_CumulativeEffectOnRetainedEarningsTax"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_OtherEquipmentMember" xlink:label="smhi_OtherEquipmentMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_NumberOfOperatingLeasesOnEquipment" xlink:label="smhi_NumberOfOperatingLeasesOnEquipment"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_MachineryAndEquipmentMember" xlink:label="us-gaap_MachineryAndEquipmentMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LesseeOperatingLeaseTermOfContract" xlink:label="us-gaap_LesseeOperatingLeaseTermOfContract"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OperatingLeaseImpairmentLoss" xlink:label="us-gaap_OperatingLeaseImpairmentLoss"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_NumberOfOperatingLeasesImpaired" xlink:label="smhi_NumberOfOperatingLeasesImpaired"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_LesseeLeaseDescriptionLineItems" xlink:to="us-gaap_LesseeLeaseDescriptionTable" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_CumulativeEffectPeriodOfAdoptionAxis" xlink:to="srt_CumulativeEffectPeriodOfAdoptionDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_RangeAxis" xlink:to="srt_RangeMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_RangeMember" xlink:to="srt_MinimumMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LesseeLeaseDescriptionLineItems" xlink:to="us-gaap_OperatingLeaseRightOfUseAsset" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_CumulativeEffectPeriodOfAdoptionDomain" xlink:to="srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_TypeOfAdoptionMember" xlink:to="us-gaap_AccountingStandardsUpdate201602Member" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_LesseeLeaseDescriptionTable" xlink:to="us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" xlink:to="us-gaap_TypeOfAdoptionMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis" xlink:to="us-gaap_ChangeInAccountingPrincipleMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:to="us-gaap_PropertyPlantAndEquipmentTypeDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ChangeInAccountingPrincipleMember" xlink:to="smhi_ChangeInAccountingPrincipleForEquipmentOfficeAndLandLeasesMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="smhi_AnchorHandlingTowingSupplyVesselMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_RangeMember" xlink:to="srt_MaximumMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LesseeLeaseDescriptionLineItems" xlink:to="us-gaap_OperatingLeaseLiability" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_LesseeLeaseDescriptionTable" xlink:to="srt_CumulativeEffectPeriodOfAdoptionAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ChangeInAccountingPrincipleMember" xlink:to="smhi_ChangeInAccountingPrincipleForUnamortizedDeferredGainsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="smhi_LiftboatsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LesseeLeaseDescriptionLineItems" xlink:to="us-gaap_RetainedEarningsAccumulatedDeficit" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_LesseeLeaseDescriptionTable" xlink:to="us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="smhi_FastSupportVesselsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LesseeLeaseDescriptionLineItems" xlink:to="smhi_CumulativeEffectOnRetainedEarningsBeforeTax" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_LesseeLeaseDescriptionTable" xlink:to="us-gaap_PropertyPlantAndEquipmentByTypeAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="smhi_VesselsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LesseeLeaseDescriptionLineItems" xlink:to="smhi_CumulativeEffectOnRetainedEarningsTax" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_LesseeLeaseDescriptionTable" xlink:to="srt_RangeAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="smhi_OtherEquipmentMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="5" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LesseeLeaseDescriptionLineItems" xlink:to="smhi_NumberOfOperatingLeasesOnEquipment" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="5" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="us-gaap_MachineryAndEquipmentMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="6" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LesseeLeaseDescriptionLineItems" xlink:to="us-gaap_LesseeOperatingLeaseTermOfContract" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="7" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LesseeLeaseDescriptionLineItems" xlink:to="us-gaap_OperatingLeaseImpairmentLoss" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="8" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LesseeLeaseDescriptionLineItems" xlink:to="smhi_NumberOfOperatingLeasesImpaired" priority="2" use="optional"/>
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.seacormarine.com/20221231/taxonomy/role/DisclosureLeasesSummaryOfFutureMinimumPaymentsForLeasesParentheticalDetails">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OperatingLeasedAssetsLineItems" xlink:label="us-gaap_OperatingLeasedAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfOperatingLeasedAssetsTable" xlink:label="us-gaap_ScheduleOfOperatingLeasedAssetsTable"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="us-gaap_SubsequentEventTypeDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SubsequentEventMember" xlink:label="us-gaap_SubsequentEventMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncreaseDecreaseInOperatingLeaseLiability" xlink:label="us-gaap_IncreaseDecreaseInOperatingLeaseLiability"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SubsequentEventTypeAxis" xlink:label="us-gaap_SubsequentEventTypeAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="us-gaap_SubsequentEventTypeDomain_default"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_OperatingLeasedAssetsLineItems" xlink:to="us-gaap_ScheduleOfOperatingLeasedAssetsTable" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SubsequentEventTypeDomain" xlink:to="us-gaap_SubsequentEventMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_OperatingLeasedAssetsLineItems" xlink:to="us-gaap_IncreaseDecreaseInOperatingLeaseLiability" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfOperatingLeasedAssetsTable" xlink:to="us-gaap_SubsequentEventTypeAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_SubsequentEventTypeAxis" xlink:to="us-gaap_SubsequentEventTypeDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_SubsequentEventTypeAxis" xlink:to="us-gaap_SubsequentEventTypeDomain_default" priority="2" use="optional"/>
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureLongTermDebtScheduleOfLongTermDebtObligationsDetails">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentTable" xlink:label="us-gaap_DebtInstrumentTable"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RecourseStatusDomain" xlink:label="us-gaap_RecourseStatusDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RecourseMember" xlink:label="us-gaap_RecourseMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentAxis" xlink:label="us-gaap_DebtInstrumentAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="us-gaap_DebtInstrumentNameDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RecourseStatusAxis" xlink:label="us-gaap_RecourseStatusAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RecourseStatusDomain" xlink:label="us-gaap_RecourseStatusDomain_default"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_ConvertibleSeniorNotesMember" xlink:label="smhi_ConvertibleSeniorNotesMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentCarryingAmount" xlink:label="us-gaap_DebtInstrumentCarryingAmount"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_NonrecourseMember" xlink:label="us-gaap_NonrecourseMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_GuaranteedNotesMember" xlink:label="smhi_GuaranteedNotesMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LongTermDebtCurrent" xlink:label="us-gaap_LongTermDebtCurrent"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_NewConvertibleNotesMember" xlink:label="smhi_NewConvertibleNotesMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentUnamortizedDiscount" xlink:label="us-gaap_DebtInstrumentUnamortizedDiscount"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_SEACORMarineForeignHoldingsCreditFacilityMember" xlink:label="smhi_SEACORMarineForeignHoldingsCreditFacilityMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DeferredFinanceCostsNoncurrentNet" xlink:label="us-gaap_DeferredFinanceCostsNoncurrentNet"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_SeaCatCrewzerIIITermLoanFacilityMember" xlink:label="smhi_SeaCatCrewzerIIITermLoanFacilityMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LongTermDebtNoncurrent" xlink:label="us-gaap_LongTermDebtNoncurrent"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_SEACOROffshoreDeltaFormerlyKnownAsSEACOSCOAcquisitionDebtMember" xlink:label="smhi_SEACOROffshoreDeltaFormerlyKnownAsSEACOSCOAcquisitionDebtMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_SEACORDeltaFormerlyKnownAsSEACOSCOShipyardFinancingMember" xlink:label="smhi_SEACORDeltaFormerlyKnownAsSEACOSCOShipyardFinancingMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_SEACORAlpineShipyardFinancingMember" xlink:label="smhi_SEACORAlpineShipyardFinancingMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_SEACOR88888TermLoanMember" xlink:label="smhi_SEACOR88888TermLoanMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_TarahumaraShipyardFinancingMember" xlink:label="smhi_TarahumaraShipyardFinancingMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_SeacorOffshoreOSVMember" xlink:label="smhi_SeacorOffshoreOSVMember"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtInstrumentTable" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RecourseStatusDomain" xlink:to="us-gaap_RecourseMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DebtInstrumentTable" xlink:to="us-gaap_DebtInstrumentAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_DebtInstrumentAxis" xlink:to="us-gaap_DebtInstrumentNameDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_RecourseStatusAxis" xlink:to="us-gaap_RecourseStatusDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_RecourseStatusAxis" xlink:to="us-gaap_RecourseStatusDomain_default" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="smhi_ConvertibleSeniorNotesMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtInstrumentCarryingAmount" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RecourseStatusDomain" xlink:to="us-gaap_NonrecourseMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DebtInstrumentTable" xlink:to="us-gaap_RecourseStatusAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="smhi_GuaranteedNotesMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_LongTermDebtCurrent" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="smhi_NewConvertibleNotesMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtInstrumentUnamortizedDiscount" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="smhi_SEACORMarineForeignHoldingsCreditFacilityMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DeferredFinanceCostsNoncurrentNet" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="smhi_SeaCatCrewzerIIITermLoanFacilityMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_LongTermDebtNoncurrent" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="5" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="smhi_SEACOROffshoreDeltaFormerlyKnownAsSEACOSCOAcquisitionDebtMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="6" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="smhi_SEACORDeltaFormerlyKnownAsSEACOSCOShipyardFinancingMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="7" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="smhi_SEACORAlpineShipyardFinancingMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="8" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="smhi_SEACOR88888TermLoanMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="9" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="smhi_TarahumaraShipyardFinancingMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="10" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="smhi_SeacorOffshoreOSVMember" priority="2" use="optional"/>
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureLongTermDebtScheduleOfLongTermDebtObligationsParentheticalDetails">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentTable" xlink:label="us-gaap_DebtInstrumentTable"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentAxis" xlink:label="us-gaap_DebtInstrumentAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="us-gaap_BusinessAcquisitionAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_SEACOSCOOffshoreLLCMember" xlink:label="smhi_SEACOSCOOffshoreLLCMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="us-gaap_DebtInstrumentNameDomain"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_SEACORDeltaFormerlyKnownAsSEACOSCOShipyardFinancingMember" xlink:label="smhi_SEACORDeltaFormerlyKnownAsSEACOSCOShipyardFinancingMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_NumberOfEquipmentAcquired" xlink:label="smhi_NumberOfEquipmentAcquired"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtInstrumentTable" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DebtInstrumentTable" xlink:to="us-gaap_DebtInstrumentAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_BusinessAcquisitionAxis" xlink:to="us-gaap_BusinessAcquisitionAcquireeDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_BusinessAcquisitionAcquireeDomain" xlink:to="smhi_SEACOSCOOffshoreLLCMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_DebtInstrumentAxis" xlink:to="us-gaap_DebtInstrumentNameDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="smhi_SEACORDeltaFormerlyKnownAsSEACOSCOShipyardFinancingMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="smhi_NumberOfEquipmentAcquired" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DebtInstrumentTable" xlink:to="us-gaap_BusinessAcquisitionAxis" priority="2" use="optional"/>
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureLongTermDebtAdditionalInformationDetails">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentTable" xlink:label="us-gaap_DebtInstrumentTable"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentAxis" xlink:label="us-gaap_DebtInstrumentAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_GuaranteeObligationsByNatureAxis" xlink:label="us-gaap_GuaranteeObligationsByNatureAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_GuaranteeObligationsNatureDomain" xlink:label="us-gaap_GuaranteeObligationsNatureDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_GuaranteeObligationsNatureDomain" xlink:label="us-gaap_GuaranteeObligationsNatureDomain_default"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="us-gaap_BusinessAcquisitionAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_MergerAgreementMember" xlink:label="smhi_MergerAgreementMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_EquityMethodInvesteeNameDomain" xlink:label="srt_EquityMethodInvesteeNameDomain"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_SEACOROffshoreDeltaFormerlyKnownAsSEACOSCOAcquisitionDebtMember" xlink:label="smhi_SEACOROffshoreDeltaFormerlyKnownAsSEACOSCOAcquisitionDebtMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_VariableRateAxis" xlink:label="us-gaap_VariableRateAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_VariableRateDomain" xlink:label="us-gaap_VariableRateDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_VariableRateDomain" xlink:label="us-gaap_VariableRateDomain_default"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TypeOfArrangementAxis" xlink:label="us-gaap_TypeOfArrangementAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="us-gaap_ArrangementsAndNonarrangementTransactionsMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentRedemptionPeriodDomain" xlink:label="us-gaap_DebtInstrumentRedemptionPeriodDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentRedemptionPeriodOneMember" xlink:label="us-gaap_DebtInstrumentRedemptionPeriodOneMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeAxis" xlink:label="srt_RangeAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeMember" xlink:label="srt_RangeMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="us-gaap_DerivativeContractTypeDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_InterestRateSwapMember" xlink:label="us-gaap_InterestRateSwapMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RepurchaseAgreementCounterpartyNameDomain" xlink:label="srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_CarlyleGroupMember" xlink:label="smhi_CarlyleGroupMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_MinimumMember" xlink:label="srt_MinimumMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LongtermDebtTypeAxis" xlink:label="us-gaap_LongtermDebtTypeAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="us-gaap_LongtermDebtTypeDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="us-gaap_LongtermDebtTypeDomain_default"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CreditFacilityDomain" xlink:label="us-gaap_CreditFacilityDomain"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_TrancheOneMember" xlink:label="smhi_TrancheOneMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CreditFacilityAxis" xlink:label="us-gaap_CreditFacilityAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfWarrantOrRightDomain" xlink:label="us-gaap_ClassOfWarrantOrRightDomain"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_CarlyleWarrantsMember" xlink:label="smhi_CarlyleWarrantsMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtConversionByUniqueDescriptionAxis" xlink:label="us-gaap_DebtConversionByUniqueDescriptionAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtConversionNameDomain" xlink:label="us-gaap_DebtConversionNameDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtConversionNameDomain" xlink:label="us-gaap_DebtConversionNameDomain_default"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xlink:label="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_TermLoanToAcquireOneVesselMember" xlink:label="smhi_TermLoanToAcquireOneVesselMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SecuredOvernightFinancingRateSofrOvernightIndexSwapRateMember" xlink:label="us-gaap_SecuredOvernightFinancingRateSofrOvernightIndexSwapRateMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="us-gaap_DebtInstrumentNameDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_CounterpartyNameAxis" xlink:label="srt_CounterpartyNameAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RepurchaseAgreementCounterpartyNameDomain" xlink:label="srt_RepurchaseAgreementCounterpartyNameDomain_default"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentRedemptionPeriodAxis" xlink:label="us-gaap_DebtInstrumentRedemptionPeriodAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentRedemptionPeriodDomain" xlink:label="us-gaap_DebtInstrumentRedemptionPeriodDomain_default"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_SeacorOffshoreOSVMember" xlink:label="smhi_SeacorOffshoreOSVMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfWarrantOrRightAxis" xlink:label="us-gaap_ClassOfWarrantOrRightAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfWarrantOrRightDomain" xlink:label="us-gaap_ClassOfWarrantOrRightDomain_default"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:label="us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_LongtermDebtObligationMember" xlink:label="smhi_LongtermDebtObligationMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_PlatformSupplyVesselsMember" xlink:label="smhi_PlatformSupplyVesselsMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_ConvertibleSeniorNotesConvertedToWarrantsMember" xlink:label="smhi_ConvertibleSeniorNotesConvertedToWarrantsMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DerivativeInstrumentRiskAxis" xlink:label="us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="us-gaap_DerivativeContractTypeDomain_default"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_LineOfCreditFacilityAssumedAndGuaranteed" xlink:label="smhi_LineOfCreditFacilityAssumedAndGuaranteed"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_CashInterestMember" xlink:label="smhi_CashInterestMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_SEACOROffshoreDeltaLLCMember" xlink:label="smhi_SEACOROffshoreDeltaLLCMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentRedemptionPeriodThreeMember" xlink:label="us-gaap_DebtInstrumentRedemptionPeriodThreeMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_DnbCapitalLlcMember" xlink:label="smhi_DnbCapitalLlcMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_MaximumMember" xlink:label="srt_MaximumMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_TrancheTwoMember" xlink:label="smhi_TrancheTwoMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_OtherThanCarlyleMember" xlink:label="smhi_OtherThanCarlyleMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_ConditionalPayoffAgreementMember" xlink:label="smhi_ConditionalPayoffAgreementMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_TermAndRevolvingLoanFacilityMember" xlink:label="smhi_TermAndRevolvingLoanFacilityMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LineOfCreditFacilityFrequencyOfPayments" xlink:label="us-gaap_LineOfCreditFacilityFrequencyOfPayments"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_HybridInterestMember" xlink:label="smhi_HybridInterestMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentRedemptionPeriodTwoMember" xlink:label="us-gaap_DebtInstrumentRedemptionPeriodTwoMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_ComericaBankMember" xlink:label="smhi_ComericaBankMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_DeferredPurchaseAgreementsMember" xlink:label="smhi_DeferredPurchaseAgreementsMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_SEACORAlpineShipyardFinancingMember" xlink:label="smhi_SEACORAlpineShipyardFinancingMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_NumberOfEquipmentAcquired" xlink:label="smhi_NumberOfEquipmentAcquired"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_HybridInterestPaidInCashMember" xlink:label="smhi_HybridInterestPaidInCashMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_TaxRefundAndIndemnificationAgreementMember" xlink:label="smhi_TaxRefundAndIndemnificationAgreementMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_WindcatWorkboatsFacilitiesMember" xlink:label="smhi_WindcatWorkboatsFacilitiesMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LineOfCreditFacilityPeriodicPaymentPrincipal" xlink:label="us-gaap_LineOfCreditFacilityPeriodicPaymentPrincipal"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_HybridInterestPaymentInKindMember" xlink:label="smhi_HybridInterestPaymentInKindMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_SaleAndPurchaseAgreementMember" xlink:label="smhi_SaleAndPurchaseAgreementMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_LoanFacilityWithDNBBankASAMember" xlink:label="smhi_LoanFacilityWithDNBBankASAMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LineOfCreditFacilityInterestRateDuringPeriod" xlink:label="us-gaap_LineOfCreditFacilityInterestRateDuringPeriod"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_OtherDNBCreditFacilitiesMember" xlink:label="smhi_OtherDNBCreditFacilitiesMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LineOfCreditFacilityExpirationDate1" xlink:label="us-gaap_LineOfCreditFacilityExpirationDate1"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_SEACORMarineForeignHoldingsCreditFacilityMember" xlink:label="smhi_SEACORMarineForeignHoldingsCreditFacilityMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LongTermDebtPercentageBearingFixedInterestRate" xlink:label="us-gaap_LongTermDebtPercentageBearingFixedInterestRate"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_ConvertibleSeniorNotesDueTwoThousandTwentyThreeMember" xlink:label="smhi_ConvertibleSeniorNotesDueTwoThousandTwentyThreeMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_DebtInstrumentMaturityYear" xlink:label="smhi_DebtInstrumentMaturityYear"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_SeniorPIKToggleNotesDueTwoThousandTwentySixMember" xlink:label="smhi_SeniorPIKToggleNotesDueTwoThousandTwentySixMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LineOfCredit" xlink:label="us-gaap_LineOfCredit"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_ConvertibleSeniorNotesDueTwoThousandTwentySixMember" xlink:label="smhi_ConvertibleSeniorNotesDueTwoThousandTwentySixMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RepaymentsOfLongTermDebt" xlink:label="us-gaap_RepaymentsOfLongTermDebt"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_GuaranteedNotesMember" xlink:label="smhi_GuaranteedNotesMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_ReimbursementAmount" xlink:label="smhi_ReimbursementAmount"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_ConvertibleSeniorNotesMember" xlink:label="smhi_ConvertibleSeniorNotesMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_NumberOfLiftboatsReleasedFromMortgagesAndSecurityArrangements" xlink:label="smhi_NumberOfLiftboatsReleasedFromMortgagesAndSecurityArrangements"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_NewConvertibleNotesMember" xlink:label="smhi_NewConvertibleNotesMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_GainsLossesOnRestructuringOfDebt" xlink:label="us-gaap_GainsLossesOnRestructuringOfDebt"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_SeaCatCrewzerIIITermLoanFacilityMember" xlink:label="smhi_SeaCatCrewzerIIITermLoanFacilityMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_TroubledDebtRestructuringDebtorCurrentPeriodIncreaseDecreaseOfBasicEarningsPerShare" xlink:label="smhi_TroubledDebtRestructuringDebtorCurrentPeriodIncreaseDecreaseOfBasicEarningsPerShare"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_TermLoanToAcquireTwoVesselsMember" xlink:label="smhi_TermLoanToAcquireTwoVesselsMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_TroubledDebtRestructuringDebtorCurrentPeriodIncreaseDecreaseOfDilutedEarningsPerShare" xlink:label="smhi_TroubledDebtRestructuringDebtorCurrentPeriodIncreaseDecreaseOfDilutedEarningsPerShare"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_SEACOR88888TermLoanMember" xlink:label="smhi_SEACOR88888TermLoanMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage" xlink:label="us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_DebtInstrumentPercentageOfFinancingOnTotalPurchasePrice" xlink:label="smhi_DebtInstrumentPercentageOfFinancingOnTotalPurchasePrice"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentTerm" xlink:label="us-gaap_DebtInstrumentTerm"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" xlink:label="us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentMaturityDate" xlink:label="us-gaap_DebtInstrumentMaturityDate"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_DebtInstrumentExtendedMaturityDate" xlink:label="smhi_DebtInstrumentExtendedMaturityDate"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_ApplicationFeePaidInConjunctionWithAmendmentAndAmortizedOverCreditFacilityTerm" xlink:label="smhi_ApplicationFeePaidInConjunctionWithAmendmentAndAmortizedOverCreditFacilityTerm"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ProceedsFromLinesOfCredit" xlink:label="us-gaap_ProceedsFromLinesOfCredit"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentIncreaseDecreaseForPeriodNet" xlink:label="us-gaap_DebtInstrumentIncreaseDecreaseForPeriodNet"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired" xlink:label="us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_PurchasePricePayableForEquityMethodInvestment" xlink:label="smhi_PurchasePricePayableForEquityMethodInvestment"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_BusinessCombinationPurchasePricePayableToSellersAtClosingOfTransaction" xlink:label="smhi_BusinessCombinationPurchasePricePayableToSellersAtClosingOfTransaction"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_PurchasePricePayableForEquityMethodInvestmentInYearOne" xlink:label="smhi_PurchasePricePayableForEquityMethodInvestmentInYearOne"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_PurchasePricePayableForEquityMethodInvestmentInYearTwo" xlink:label="smhi_PurchasePricePayableForEquityMethodInvestmentInYearTwo"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_PurchasePricePayableForEquityMethodInvestmentInYearThree" xlink:label="smhi_PurchasePricePayableForEquityMethodInvestmentInYearThree"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_PurchasePricePayableForEquityMethodInvestmentInYearFour" xlink:label="smhi_PurchasePricePayableForEquityMethodInvestmentInYearFour"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_PercentageOfPurchasePriceFixedAccruedInterestRateForEquityMethodInvestmentInYearOne" xlink:label="smhi_PercentageOfPurchasePriceFixedAccruedInterestRateForEquityMethodInvestmentInYearOne"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_PercentageOfPurchasePriceFixedAccruedInterestRateForEquityMethodInvestmentInYearTwo" xlink:label="smhi_PercentageOfPurchasePriceFixedAccruedInterestRateForEquityMethodInvestmentInYearTwo"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_PercentageOfPurchasePriceFixedAccruedInterestRateForEquityMethodInvestmentInYearThree" xlink:label="smhi_PercentageOfPurchasePriceFixedAccruedInterestRateForEquityMethodInvestmentInYearThree"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_PercentageOfPurchasePriceFixedAccruedInterestRateForEquityMethodInvestmentInYearFour" xlink:label="smhi_PercentageOfPurchasePriceFixedAccruedInterestRateForEquityMethodInvestmentInYearFour"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_BusinessAcquisitionPurchasePriceAmortizationPeriod" xlink:label="smhi_BusinessAcquisitionPurchasePriceAmortizationPeriod"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentDescriptionOfVariableRateBasis" xlink:label="us-gaap_DebtInstrumentDescriptionOfVariableRateBasis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1" xlink:label="us-gaap_DebtInstrumentBasisSpreadOnVariableRate1"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_EquityMethodInvestmentPurchasePriceAmortizationPeriod" xlink:label="smhi_EquityMethodInvestmentPurchasePriceAmortizationPeriod"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RepaymentsOfLinesOfCredit" xlink:label="us-gaap_RepaymentsOfLinesOfCredit"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LongTermDebt" xlink:label="us-gaap_LongTermDebt"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_InterestPayableCurrentAndNoncurrent" xlink:label="us-gaap_InterestPayableCurrentAndNoncurrent"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentPeriodicPaymentPrincipal" xlink:label="us-gaap_DebtInstrumentPeriodicPaymentPrincipal"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebt" xlink:label="us-gaap_GainsLossesOnExtinguishmentOfDebt"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DerivativeNotionalAmount" xlink:label="us-gaap_DerivativeNotionalAmount"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_NumberOfAdditionalVesselsOwned" xlink:label="smhi_NumberOfAdditionalVesselsOwned"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_EstimatedCashOrCashEquivalentsTaxRefundsReceivable" xlink:label="smhi_EstimatedCashOrCashEquivalentsTaxRefundsReceivable"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPercentage" xlink:label="smhi_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPercentage"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents" xlink:label="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_LoanPrincipalAmount" xlink:label="smhi_LoanPrincipalAmount"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_PercentageOfLongTermDebtIncreaseInMargin" xlink:label="smhi_PercentageOfLongTermDebtIncreaseInMargin"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ConvertibleDebt" xlink:label="us-gaap_ConvertibleDebt"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentConvertibleConversionRatio1" xlink:label="us-gaap_DebtInstrumentConvertibleConversionRatio1"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1" xlink:label="us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EmbeddedDerivativeFairValueOfEmbeddedDerivativeLiability" xlink:label="us-gaap_EmbeddedDerivativeFairValueOfEmbeddedDerivativeLiability"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentInterestRateEffectivePercentage" xlink:label="us-gaap_DebtInstrumentInterestRateEffectivePercentage"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_NumberOfVesselsOwned" xlink:label="smhi_NumberOfVesselsOwned"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_NumberOfVesselsDeliveredToCompany" xlink:label="smhi_NumberOfVesselsDeliveredToCompany"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtConversionOriginalDebtAmount1" xlink:label="us-gaap_DebtConversionOriginalDebtAmount1"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtConversionConvertedInstrumentSharesIssued1" xlink:label="us-gaap_DebtConversionConvertedInstrumentSharesIssued1"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentConvertibleConversionPrice1" xlink:label="us-gaap_DebtInstrumentConvertibleConversionPrice1"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_WarrantsAndRightsOutstandingTerm" xlink:label="us-gaap_WarrantsAndRightsOutstandingTerm"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_NotesRedeemableDenominationAmount" xlink:label="smhi_NotesRedeemableDenominationAmount"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentRedemptionDescription" xlink:label="us-gaap_DebtInstrumentRedemptionDescription"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentRedemptionPricePercentage" xlink:label="us-gaap_DebtInstrumentRedemptionPricePercentage"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_ConvertibleNotesOutstanding" xlink:label="smhi_ConvertibleNotesOutstanding"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentFaceAmount" xlink:label="us-gaap_DebtInstrumentFaceAmount"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_DebtInstrumentConversionPricePercentage" xlink:label="smhi_DebtInstrumentConversionPricePercentage"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentConvertibleTermsOfConversionFeature" xlink:label="us-gaap_DebtInstrumentConvertibleTermsOfConversionFeature"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_DebtInstrumentPercentageOfNewConvertibleNotesToBePurchased" xlink:label="smhi_DebtInstrumentPercentageOfNewConvertibleNotesToBePurchased"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_DebtInstrumentPercentageOfNewConvertibleNoteToBePurchased" xlink:label="smhi_DebtInstrumentPercentageOfNewConvertibleNoteToBePurchased"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_DebtInstrumentPercentageOfNewConvertibleNoteToBeRedeemed" xlink:label="smhi_DebtInstrumentPercentageOfNewConvertibleNoteToBeRedeemed"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_DebtInstrumentPercentageOfNewConvertibleNotesToBeRedeemed" xlink:label="smhi_DebtInstrumentPercentageOfNewConvertibleNotesToBeRedeemed"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ProceedsFromIssuanceOfDebt" xlink:label="us-gaap_ProceedsFromIssuanceOfDebt"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DeferredFinanceCostsGross" xlink:label="us-gaap_DeferredFinanceCostsGross"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_ClaimsRecoverableAmountUnderBorrowings" xlink:label="smhi_ClaimsRecoverableAmountUnderBorrowings"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SecuredDebt" xlink:label="us-gaap_SecuredDebt"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_PercentageOfDebtObligationsOutstanding" xlink:label="smhi_PercentageOfDebtObligationsOutstanding"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_ClaimsRecoverableUnderBorrowingsPercentageOfObligationsOutstanding" xlink:label="smhi_ClaimsRecoverableUnderBorrowingsPercentageOfObligationsOutstanding"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LettersOfCreditOutstandingAmount" xlink:label="us-gaap_LettersOfCreditOutstandingAmount"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentUnamortizedDiscount" xlink:label="us-gaap_DebtInstrumentUnamortizedDiscount"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DeferredFinanceCostsNet" xlink:label="us-gaap_DeferredFinanceCostsNet"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentConvertibleCarryingAmountOfTheEquityComponent" xlink:label="us-gaap_DebtInstrumentConvertibleCarryingAmountOfTheEquityComponent"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AmortizationOfFinancingCostsAndDiscounts" xlink:label="us-gaap_AmortizationOfFinancingCostsAndDiscounts"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_InterestExpenseDebtExcludingAmortization" xlink:label="us-gaap_InterestExpenseDebtExcludingAmortization"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_InterestExpenseDebt" xlink:label="us-gaap_InterestExpenseDebt"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtInstrumentTable" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DebtInstrumentTable" xlink:to="us-gaap_DebtInstrumentAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_GuaranteeObligationsByNatureAxis" xlink:to="us-gaap_GuaranteeObligationsNatureDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_GuaranteeObligationsByNatureAxis" xlink:to="us-gaap_GuaranteeObligationsNatureDomain_default" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_BusinessAcquisitionAxis" xlink:to="us-gaap_BusinessAcquisitionAcquireeDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_BusinessAcquisitionAcquireeDomain" xlink:to="smhi_MergerAgreementMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_EquityMethodInvesteeNameDomain" xlink:to="smhi_SEACOROffshoreDeltaFormerlyKnownAsSEACOSCOAcquisitionDebtMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_VariableRateAxis" xlink:to="us-gaap_VariableRateDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_VariableRateAxis" xlink:to="us-gaap_VariableRateDomain_default" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_TypeOfArrangementAxis" xlink:to="us-gaap_ArrangementsAndNonarrangementTransactionsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentRedemptionPeriodDomain" xlink:to="us-gaap_DebtInstrumentRedemptionPeriodOneMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_RangeAxis" xlink:to="srt_RangeMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DerivativeContractTypeDomain" xlink:to="us-gaap_InterestRateSwapMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_RepurchaseAgreementCounterpartyNameDomain" xlink:to="smhi_CarlyleGroupMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_RangeMember" xlink:to="srt_MinimumMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_LongtermDebtTypeAxis" xlink:to="us-gaap_LongtermDebtTypeDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_LongtermDebtTypeAxis" xlink:to="us-gaap_LongtermDebtTypeDomain_default" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_CreditFacilityDomain" xlink:to="smhi_TrancheOneMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_CreditFacilityAxis" xlink:to="us-gaap_CreditFacilityDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfWarrantOrRightDomain" xlink:to="smhi_CarlyleWarrantsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_DebtConversionByUniqueDescriptionAxis" xlink:to="us-gaap_DebtConversionNameDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_DebtConversionByUniqueDescriptionAxis" xlink:to="us-gaap_DebtConversionNameDomain_default" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xlink:to="srt_EquityMethodInvesteeNameDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:to="smhi_TermLoanToAcquireOneVesselMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_VariableRateDomain" xlink:to="us-gaap_SecuredOvernightFinancingRateSofrOvernightIndexSwapRateMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_DebtInstrumentAxis" xlink:to="us-gaap_DebtInstrumentNameDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_CounterpartyNameAxis" xlink:to="srt_RepurchaseAgreementCounterpartyNameDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="srt_CounterpartyNameAxis" xlink:to="srt_RepurchaseAgreementCounterpartyNameDomain_default" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_DebtInstrumentRedemptionPeriodAxis" xlink:to="us-gaap_DebtInstrumentRedemptionPeriodDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_DebtInstrumentRedemptionPeriodAxis" xlink:to="us-gaap_DebtInstrumentRedemptionPeriodDomain_default" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="smhi_SeacorOffshoreOSVMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_ClassOfWarrantOrRightAxis" xlink:to="us-gaap_ClassOfWarrantOrRightDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_ClassOfWarrantOrRightAxis" xlink:to="us-gaap_ClassOfWarrantOrRightDomain_default" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:to="us-gaap_PropertyPlantAndEquipmentTypeDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_GuaranteeObligationsNatureDomain" xlink:to="smhi_LongtermDebtObligationMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="smhi_PlatformSupplyVesselsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtConversionNameDomain" xlink:to="smhi_ConvertibleSeniorNotesConvertedToWarrantsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_DerivativeInstrumentRiskAxis" xlink:to="us-gaap_DerivativeContractTypeDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_DerivativeInstrumentRiskAxis" xlink:to="us-gaap_DerivativeContractTypeDomain_default" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="smhi_LineOfCreditFacilityAssumedAndGuaranteed" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LongtermDebtTypeDomain" xlink:to="smhi_CashInterestMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DebtInstrumentTable" xlink:to="us-gaap_TypeOfArrangementAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_EquityMethodInvesteeNameDomain" xlink:to="smhi_SEACOROffshoreDeltaLLCMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentRedemptionPeriodDomain" xlink:to="us-gaap_DebtInstrumentRedemptionPeriodThreeMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_RepurchaseAgreementCounterpartyNameDomain" xlink:to="smhi_DnbCapitalLlcMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_RangeMember" xlink:to="srt_MaximumMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_CreditFacilityDomain" xlink:to="smhi_TrancheTwoMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfWarrantOrRightDomain" xlink:to="smhi_OtherThanCarlyleMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:to="smhi_ConditionalPayoffAgreementMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="smhi_TermAndRevolvingLoanFacilityMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_LineOfCreditFacilityFrequencyOfPayments" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LongtermDebtTypeDomain" xlink:to="smhi_HybridInterestMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DebtInstrumentTable" xlink:to="us-gaap_DebtInstrumentRedemptionPeriodAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentRedemptionPeriodDomain" xlink:to="us-gaap_DebtInstrumentRedemptionPeriodTwoMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_RepurchaseAgreementCounterpartyNameDomain" xlink:to="smhi_ComericaBankMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:to="smhi_DeferredPurchaseAgreementsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="smhi_SEACORAlpineShipyardFinancingMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="smhi_NumberOfEquipmentAcquired" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LongtermDebtTypeDomain" xlink:to="smhi_HybridInterestPaidInCashMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DebtInstrumentTable" xlink:to="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:to="smhi_TaxRefundAndIndemnificationAgreementMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="smhi_WindcatWorkboatsFacilitiesMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_LineOfCreditFacilityPeriodicPaymentPrincipal" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LongtermDebtTypeDomain" xlink:to="smhi_HybridInterestPaymentInKindMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DebtInstrumentTable" xlink:to="us-gaap_BusinessAcquisitionAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:to="smhi_SaleAndPurchaseAgreementMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="smhi_LoanFacilityWithDNBBankASAMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_LineOfCreditFacilityInterestRateDuringPeriod" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="5" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DebtInstrumentTable" xlink:to="us-gaap_PropertyPlantAndEquipmentByTypeAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="5" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="smhi_OtherDNBCreditFacilitiesMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="5" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_LineOfCreditFacilityExpirationDate1" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="6" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DebtInstrumentTable" xlink:to="us-gaap_DerivativeInstrumentRiskAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="6" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="smhi_SEACORMarineForeignHoldingsCreditFacilityMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="6" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_LongTermDebtPercentageBearingFixedInterestRate" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="7" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DebtInstrumentTable" xlink:to="srt_RangeAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="7" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="smhi_ConvertibleSeniorNotesDueTwoThousandTwentyThreeMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="7" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="smhi_DebtInstrumentMaturityYear" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="8" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DebtInstrumentTable" xlink:to="us-gaap_VariableRateAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="8" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="smhi_SeniorPIKToggleNotesDueTwoThousandTwentySixMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="8" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_LineOfCredit" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="9" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DebtInstrumentTable" xlink:to="us-gaap_CreditFacilityAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="9" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="smhi_ConvertibleSeniorNotesDueTwoThousandTwentySixMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="9" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_RepaymentsOfLongTermDebt" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="10" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DebtInstrumentTable" xlink:to="us-gaap_ClassOfWarrantOrRightAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="10" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="smhi_GuaranteedNotesMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="10" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="smhi_ReimbursementAmount" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="11" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DebtInstrumentTable" xlink:to="us-gaap_DebtConversionByUniqueDescriptionAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="11" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="smhi_ConvertibleSeniorNotesMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="11" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="smhi_NumberOfLiftboatsReleasedFromMortgagesAndSecurityArrangements" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="12" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DebtInstrumentTable" xlink:to="srt_CounterpartyNameAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="12" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="smhi_NewConvertibleNotesMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="12" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_GainsLossesOnRestructuringOfDebt" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="13" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DebtInstrumentTable" xlink:to="us-gaap_LongtermDebtTypeAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="13" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="smhi_SeaCatCrewzerIIITermLoanFacilityMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="13" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="smhi_TroubledDebtRestructuringDebtorCurrentPeriodIncreaseDecreaseOfBasicEarningsPerShare" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="14" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DebtInstrumentTable" xlink:to="us-gaap_GuaranteeObligationsByNatureAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="14" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="smhi_TermLoanToAcquireTwoVesselsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="14" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="smhi_TroubledDebtRestructuringDebtorCurrentPeriodIncreaseDecreaseOfDilutedEarningsPerShare" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="15" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="smhi_SEACOR88888TermLoanMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="15" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtInstrumentInterestRateStatedPercentage" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="16" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="smhi_DebtInstrumentPercentageOfFinancingOnTotalPurchasePrice" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="17" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtInstrumentTerm" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="18" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="19" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtInstrumentMaturityDate" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="20" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="smhi_DebtInstrumentExtendedMaturityDate" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="21" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="smhi_ApplicationFeePaidInConjunctionWithAmendmentAndAmortizedOverCreditFacilityTerm" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="22" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_ProceedsFromLinesOfCredit" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="23" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtInstrumentIncreaseDecreaseForPeriodNet" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="24" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="25" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="smhi_PurchasePricePayableForEquityMethodInvestment" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="26" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="smhi_BusinessCombinationPurchasePricePayableToSellersAtClosingOfTransaction" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="27" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="smhi_PurchasePricePayableForEquityMethodInvestmentInYearOne" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="28" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="smhi_PurchasePricePayableForEquityMethodInvestmentInYearTwo" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="29" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="smhi_PurchasePricePayableForEquityMethodInvestmentInYearThree" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="30" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="smhi_PurchasePricePayableForEquityMethodInvestmentInYearFour" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="31" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="smhi_PercentageOfPurchasePriceFixedAccruedInterestRateForEquityMethodInvestmentInYearOne" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="32" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="smhi_PercentageOfPurchasePriceFixedAccruedInterestRateForEquityMethodInvestmentInYearTwo" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="33" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="smhi_PercentageOfPurchasePriceFixedAccruedInterestRateForEquityMethodInvestmentInYearThree" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="34" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="smhi_PercentageOfPurchasePriceFixedAccruedInterestRateForEquityMethodInvestmentInYearFour" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="35" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="36" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="smhi_BusinessAcquisitionPurchasePriceAmortizationPeriod" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="37" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtInstrumentDescriptionOfVariableRateBasis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="38" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtInstrumentBasisSpreadOnVariableRate1" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="39" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="smhi_EquityMethodInvestmentPurchasePriceAmortizationPeriod" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="40" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_RepaymentsOfLinesOfCredit" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="41" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_LongTermDebt" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="42" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_InterestPayableCurrentAndNoncurrent" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="43" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtInstrumentPeriodicPaymentPrincipal" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="44" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_GainsLossesOnExtinguishmentOfDebt" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="45" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DerivativeNotionalAmount" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="46" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="smhi_NumberOfAdditionalVesselsOwned" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="47" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="smhi_EstimatedCashOrCashEquivalentsTaxRefundsReceivable" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="48" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="smhi_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPercentage" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="49" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="50" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="smhi_LoanPrincipalAmount" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="51" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="smhi_PercentageOfLongTermDebtIncreaseInMargin" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="52" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_ConvertibleDebt" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="53" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtInstrumentConvertibleConversionRatio1" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="54" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="55" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_EmbeddedDerivativeFairValueOfEmbeddedDerivativeLiability" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="56" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtInstrumentInterestRateEffectivePercentage" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="57" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="smhi_NumberOfVesselsOwned" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="58" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="smhi_NumberOfVesselsDeliveredToCompany" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="59" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtConversionOriginalDebtAmount1" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="60" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtConversionConvertedInstrumentSharesIssued1" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="61" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtInstrumentConvertibleConversionPrice1" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="62" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_WarrantsAndRightsOutstandingTerm" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="63" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="smhi_NotesRedeemableDenominationAmount" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="64" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtInstrumentRedemptionDescription" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="65" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtInstrumentRedemptionPricePercentage" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="66" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="smhi_ConvertibleNotesOutstanding" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="67" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtInstrumentFaceAmount" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="68" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="smhi_DebtInstrumentConversionPricePercentage" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="69" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtInstrumentConvertibleTermsOfConversionFeature" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="70" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="smhi_DebtInstrumentPercentageOfNewConvertibleNotesToBePurchased" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="71" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="smhi_DebtInstrumentPercentageOfNewConvertibleNoteToBePurchased" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="72" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="smhi_DebtInstrumentPercentageOfNewConvertibleNoteToBeRedeemed" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="73" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="smhi_DebtInstrumentPercentageOfNewConvertibleNotesToBeRedeemed" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="74" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_ProceedsFromIssuanceOfDebt" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="75" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DeferredFinanceCostsGross" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="76" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="smhi_ClaimsRecoverableAmountUnderBorrowings" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="77" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_SecuredDebt" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="78" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="smhi_PercentageOfDebtObligationsOutstanding" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="79" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="smhi_ClaimsRecoverableUnderBorrowingsPercentageOfObligationsOutstanding" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="80" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_LettersOfCreditOutstandingAmount" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="81" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtInstrumentUnamortizedDiscount" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="82" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DeferredFinanceCostsNet" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="83" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtInstrumentConvertibleCarryingAmountOfTheEquityComponent" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="84" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_AmortizationOfFinancingCostsAndDiscounts" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="85" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_InterestExpenseDebtExcludingAmortization" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="86" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_InterestExpenseDebt" priority="2" use="optional"/>
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureLongTermDebtScheduleOfGainOnTransactionsUnderConditionalPayoffAgreementDetails">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentTable" xlink:label="us-gaap_DebtInstrumentTable"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentAxis" xlink:label="us-gaap_DebtInstrumentAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TypeOfArrangementAxis" xlink:label="us-gaap_TypeOfArrangementAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="us-gaap_ArrangementsAndNonarrangementTransactionsMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_ConditionalPayoffAgreementMember" xlink:label="smhi_ConditionalPayoffAgreementMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="us-gaap_DebtInstrumentNameDomain"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_FalconGlobalUSATermLoanFacilityMember" xlink:label="smhi_FalconGlobalUSATermLoanFacilityMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentCarryingAmount" xlink:label="us-gaap_DebtInstrumentCarryingAmount"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_FalconGlobalUSARevolverMember" xlink:label="smhi_FalconGlobalUSARevolverMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentUnamortizedDiscount" xlink:label="us-gaap_DebtInstrumentUnamortizedDiscount"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtCurrent" xlink:label="us-gaap_DebtCurrent"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentFeeAmount" xlink:label="us-gaap_DebtInstrumentFeeAmount"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RepaymentsOfLongTermDebt" xlink:label="us-gaap_RepaymentsOfLongTermDebt"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_HullAndMachineryInsuranceProceeds" xlink:label="smhi_HullAndMachineryInsuranceProceeds"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TroubledDebtRestructuringDebtorCurrentPeriodGainLossOnRestructuringNetOfTax" xlink:label="us-gaap_TroubledDebtRestructuringDebtorCurrentPeriodGainLossOnRestructuringNetOfTax"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtInstrumentTable" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DebtInstrumentTable" xlink:to="us-gaap_DebtInstrumentAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_TypeOfArrangementAxis" xlink:to="us-gaap_ArrangementsAndNonarrangementTransactionsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:to="smhi_ConditionalPayoffAgreementMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_DebtInstrumentAxis" xlink:to="us-gaap_DebtInstrumentNameDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="smhi_FalconGlobalUSATermLoanFacilityMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtInstrumentCarryingAmount" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DebtInstrumentTable" xlink:to="us-gaap_TypeOfArrangementAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="smhi_FalconGlobalUSARevolverMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtInstrumentUnamortizedDiscount" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtCurrent" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtInstrumentFeeAmount" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_RepaymentsOfLongTermDebt" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="5" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="smhi_HullAndMachineryInsuranceProceeds" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="6" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_TroubledDebtRestructuringDebtorCurrentPeriodGainLossOnRestructuringNetOfTax" priority="2" use="optional"/>
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureIncomeTaxesAdditionalInformationDetails">
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_IncomeTaxesLineItems" xlink:label="smhi_IncomeTaxesLineItems"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_IncomeTaxesTable" xlink:label="smhi_IncomeTaxesTable"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TypeOfArrangementAxis" xlink:label="us-gaap_TypeOfArrangementAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="us-gaap_ArrangementsAndNonarrangementTransactionsMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_TaxRefundAndIndemnificationAgreementMember" xlink:label="smhi_TaxRefundAndIndemnificationAgreementMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ProceedsFromIncomeTaxRefunds" xlink:label="us-gaap_ProceedsFromIncomeTaxRefunds"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_InterestReceivedOnCashRefunds" xlink:label="smhi_InterestReceivedOnCashRefunds"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_PercentageOfNetOperatingLossesFacilitateTaxSavings" xlink:label="smhi_PercentageOfNetOperatingLossesFacilitateTaxSavings"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_TransactionFee" xlink:label="smhi_TransactionFee"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_CashTaxRefundsWithoutRestrictionsToUse" xlink:label="smhi_CashTaxRefundsWithoutRestrictionsToUse"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_CashTaxRefundsWithRestrictionsToUse" xlink:label="smhi_CashTaxRefundsWithRestrictionsToUse"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationEquityInEarningsLossesOfUnconsolidatedSubsidiary" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationEquityInEarningsLossesOfUnconsolidatedSubsidiary"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncomeTaxReconciliationTaxCreditsForeign" xlink:label="us-gaap_IncomeTaxReconciliationTaxCreditsForeign"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncomeTaxExaminationLiabilityRefundAdjustmentFromSettlementWithTaxingAuthority" xlink:label="us-gaap_IncomeTaxExaminationLiabilityRefundAdjustmentFromSettlementWithTaxingAuthority"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_IncreaseDecreaseInTransitionTaxLiability" xlink:label="smhi_IncreaseDecreaseInTransitionTaxLiability"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EffectiveIncomeTaxRateContinuingOperations" xlink:label="us-gaap_EffectiveIncomeTaxRateContinuingOperations"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate" xlink:label="us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_InterestExpenseSuspended" xlink:label="smhi_InterestExpenseSuspended"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_InterestExpenseSuspendedDeductible" xlink:label="smhi_InterestExpenseSuspendedDeductible"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_InterestExpenseCarryforward" xlink:label="smhi_InterestExpenseCarryforward"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_InterestExpenseSuspendedLimitationPercentage" xlink:label="smhi_InterestExpenseSuspendedLimitationPercentage"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_OperatingLossCarryforwardsPercentageOfTaxableIncomeUtilizationLimitation" xlink:label="smhi_OperatingLossCarryforwardsPercentageOfTaxableIncomeUtilizationLimitation"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OperatingLossCarryforwards" xlink:label="us-gaap_OperatingLossCarryforwards"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_OperatingLossCarryforwardsExpirationPeriod" xlink:label="smhi_OperatingLossCarryforwardsExpirationPeriod"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_OperatingLossCarryForwardsExpirationYear" xlink:label="smhi_OperatingLossCarryForwardsExpirationYear"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OperatingLossCarryforwardsValuationAllowance" xlink:label="us-gaap_OperatingLossCarryforwardsValuationAllowance"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="smhi_IncomeTaxesLineItems" xlink:to="smhi_IncomeTaxesTable" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_TypeOfArrangementAxis" xlink:to="us-gaap_ArrangementsAndNonarrangementTransactionsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:to="smhi_TaxRefundAndIndemnificationAgreementMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="smhi_IncomeTaxesTable" xlink:to="us-gaap_TypeOfArrangementAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_IncomeTaxesLineItems" xlink:to="us-gaap_ProceedsFromIncomeTaxRefunds" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_IncomeTaxesLineItems" xlink:to="smhi_InterestReceivedOnCashRefunds" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_IncomeTaxesLineItems" xlink:to="smhi_PercentageOfNetOperatingLossesFacilitateTaxSavings" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_IncomeTaxesLineItems" xlink:to="smhi_TransactionFee" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_IncomeTaxesLineItems" xlink:to="smhi_CashTaxRefundsWithoutRestrictionsToUse" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="5" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_IncomeTaxesLineItems" xlink:to="smhi_CashTaxRefundsWithRestrictionsToUse" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="6" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_IncomeTaxesLineItems" xlink:to="us-gaap_EffectiveIncomeTaxRateReconciliationEquityInEarningsLossesOfUnconsolidatedSubsidiary" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="7" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_IncomeTaxesLineItems" xlink:to="us-gaap_IncomeTaxReconciliationTaxCreditsForeign" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="8" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_IncomeTaxesLineItems" xlink:to="us-gaap_IncomeTaxExaminationLiabilityRefundAdjustmentFromSettlementWithTaxingAuthority" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="9" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_IncomeTaxesLineItems" xlink:to="smhi_IncreaseDecreaseInTransitionTaxLiability" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="10" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_IncomeTaxesLineItems" xlink:to="us-gaap_EffectiveIncomeTaxRateContinuingOperations" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="11" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_IncomeTaxesLineItems" xlink:to="us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="12" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_IncomeTaxesLineItems" xlink:to="smhi_InterestExpenseSuspended" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="13" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_IncomeTaxesLineItems" xlink:to="smhi_InterestExpenseSuspendedDeductible" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="14" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_IncomeTaxesLineItems" xlink:to="smhi_InterestExpenseCarryforward" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="15" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_IncomeTaxesLineItems" xlink:to="smhi_InterestExpenseSuspendedLimitationPercentage" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="16" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_IncomeTaxesLineItems" xlink:to="smhi_OperatingLossCarryforwardsPercentageOfTaxableIncomeUtilizationLimitation" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="17" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_IncomeTaxesLineItems" xlink:to="us-gaap_OperatingLossCarryforwards" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="18" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_IncomeTaxesLineItems" xlink:to="smhi_OperatingLossCarryforwardsExpirationPeriod" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="19" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_IncomeTaxesLineItems" xlink:to="smhi_OperatingLossCarryForwardsExpirationYear" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="20" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_IncomeTaxesLineItems" xlink:to="us-gaap_OperatingLossCarryforwardsValuationAllowance" priority="2" use="optional"/>
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.seacormarine.com/20221231/taxonomy/role/DisclosureIncomeTaxesScheduleOfLossIncomeBeforeIncomeTaxExpenseBenefitDetails">
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_IncomeTaxesLineItems" xlink:label="smhi_IncomeTaxesLineItems"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_IncomeTaxesTable" xlink:label="smhi_IncomeTaxesTable"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncomeTaxAuthorityDomain" xlink:label="us-gaap_IncomeTaxAuthorityDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DomesticCountryMember" xlink:label="us-gaap_DomesticCountryMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncomeTaxAuthorityAxis" xlink:label="us-gaap_IncomeTaxAuthorityAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncomeTaxAuthorityDomain" xlink:label="us-gaap_IncomeTaxAuthorityDomain_default"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments" xlink:label="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ForeignCountryMember" xlink:label="us-gaap_ForeignCountryMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_EliminationsMember" xlink:label="smhi_EliminationsMember"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="smhi_IncomeTaxesLineItems" xlink:to="smhi_IncomeTaxesTable" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncomeTaxAuthorityDomain" xlink:to="us-gaap_DomesticCountryMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_IncomeTaxAuthorityAxis" xlink:to="us-gaap_IncomeTaxAuthorityDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_IncomeTaxAuthorityAxis" xlink:to="us-gaap_IncomeTaxAuthorityDomain_default" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="smhi_IncomeTaxesTable" xlink:to="us-gaap_IncomeTaxAuthorityAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_IncomeTaxesLineItems" xlink:to="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncomeTaxAuthorityDomain" xlink:to="us-gaap_ForeignCountryMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncomeTaxAuthorityDomain" xlink:to="smhi_EliminationsMember" priority="2" use="optional"/>
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureDerivativeInstrumentsAndHedgingStrategiesScheduleOfFairValueOfDerivativeAssetsAndLiabilitiesDetails">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DerivativeLineItems" xlink:label="us-gaap_DerivativeLineItems"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DerivativeTable" xlink:label="us-gaap_DerivativeTable"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_HedgingRelationshipDomain" xlink:label="us-gaap_HedgingRelationshipDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CashFlowHedgingMember" xlink:label="us-gaap_CashFlowHedgingMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis" xlink:label="us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_HedgingRelationshipDomain" xlink:label="us-gaap_HedgingRelationshipDomain_default"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="us-gaap_DerivativeContractTypeDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_InterestRateSwapMember" xlink:label="us-gaap_InterestRateSwapMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DerivativeAssets" xlink:label="us-gaap_DerivativeAssets"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_HedgingDesignationAxis" xlink:label="us-gaap_HedgingDesignationAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_HedgingDesignationDomain" xlink:label="us-gaap_HedgingDesignationDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_HedgingDesignationDomain" xlink:label="us-gaap_HedgingDesignationDomain_default"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DesignatedAsHedgingInstrumentMember" xlink:label="us-gaap_DesignatedAsHedgingInstrumentMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DerivativeInstrumentRiskAxis" xlink:label="us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ForeignExchangeForwardMember" xlink:label="us-gaap_ForeignExchangeForwardMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DerivativeAssetStatementOfFinancialPositionExtensibleEnumeration" xlink:label="us-gaap_DerivativeAssetStatementOfFinancialPositionExtensibleEnumeration"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_NondesignatedMember" xlink:label="us-gaap_NondesignatedMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DerivativeLiabilities" xlink:label="us-gaap_DerivativeLiabilities"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DerivativeLiabilityStatementOfFinancialPositionExtensibleEnumeration" xlink:label="us-gaap_DerivativeLiabilityStatementOfFinancialPositionExtensibleEnumeration"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EmbeddedDerivativeFairValueOfEmbeddedDerivativeLiability" xlink:label="us-gaap_EmbeddedDerivativeFairValueOfEmbeddedDerivativeLiability"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_DerivativeLineItems" xlink:to="us-gaap_DerivativeTable" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_HedgingRelationshipDomain" xlink:to="us-gaap_CashFlowHedgingMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis" xlink:to="us-gaap_HedgingRelationshipDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis" xlink:to="us-gaap_HedgingRelationshipDomain_default" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DerivativeContractTypeDomain" xlink:to="us-gaap_InterestRateSwapMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DerivativeLineItems" xlink:to="us-gaap_DerivativeAssets" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DerivativeTable" xlink:to="us-gaap_HedgingDesignationAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_HedgingDesignationAxis" xlink:to="us-gaap_HedgingDesignationDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_HedgingDesignationAxis" xlink:to="us-gaap_HedgingDesignationDomain_default" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_HedgingDesignationDomain" xlink:to="us-gaap_DesignatedAsHedgingInstrumentMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_DerivativeInstrumentRiskAxis" xlink:to="us-gaap_DerivativeContractTypeDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DerivativeContractTypeDomain" xlink:to="us-gaap_ForeignExchangeForwardMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DerivativeLineItems" xlink:to="us-gaap_DerivativeAssetStatementOfFinancialPositionExtensibleEnumeration" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DerivativeTable" xlink:to="us-gaap_DerivativeInstrumentRiskAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_HedgingDesignationDomain" xlink:to="us-gaap_NondesignatedMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DerivativeLineItems" xlink:to="us-gaap_DerivativeLiabilities" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DerivativeTable" xlink:to="us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DerivativeLineItems" xlink:to="us-gaap_DerivativeLiabilityStatementOfFinancialPositionExtensibleEnumeration" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DerivativeLineItems" xlink:to="us-gaap_EmbeddedDerivativeFairValueOfEmbeddedDerivativeLiability" priority="2" use="optional"/>
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureDerivativeInstrumentsAndHedgingStrategiesAdditionalInformationDetails">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DerivativeLineItems" xlink:label="us-gaap_DerivativeLineItems"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DerivativeTable" xlink:label="us-gaap_DerivativeTable"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_HedgingRelationshipDomain" xlink:label="us-gaap_HedgingRelationshipDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueHedgingMember" xlink:label="us-gaap_FairValueHedgingMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_EquityMethodInvesteeNameDomain" xlink:label="srt_EquityMethodInvesteeNameDomain"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_EquityInvestmentsIn50OrLessOwnedCompaniesMember" xlink:label="smhi_EquityInvestmentsIn50OrLessOwnedCompaniesMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis" xlink:label="us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeAxis" xlink:label="srt_RangeAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeMember" xlink:label="srt_RangeMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="us-gaap_DerivativeContractTypeDomain"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_InterestRateSwapAgreementThreePointThreeTwoPercentMember" xlink:label="smhi_InterestRateSwapAgreementThreePointThreeTwoPercentMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ChangeInUnrealizedGainLossOnHedgedItemInFairValueHedge1" xlink:label="us-gaap_ChangeInUnrealizedGainLossOnHedgedItemInFairValueHedge1"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueByLiabilityClassAxis" xlink:label="us-gaap_FairValueByLiabilityClassAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_MaximumMember" xlink:label="srt_MaximumMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:label="us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:label="us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_default"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DerivativeFinancialInstrumentsLiabilitiesMember" xlink:label="us-gaap_DerivativeFinancialInstrumentsLiabilitiesMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xlink:label="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_HedgingDesignationAxis" xlink:label="us-gaap_HedgingDesignationAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_HedgingDesignationDomain" xlink:label="us-gaap_HedgingDesignationDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DesignatedAsHedgingInstrumentMember" xlink:label="us-gaap_DesignatedAsHedgingInstrumentMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_SEACORMarineForeignHoldingsMember" xlink:label="smhi_SEACORMarineForeignHoldingsMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DerivativeInstrumentRiskAxis" xlink:label="us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CashFlowHedgingMember" xlink:label="us-gaap_CashFlowHedgingMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_MexMarMember" xlink:label="smhi_MexMarMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_InterestRateSwapAgreementThreePointOneNineFivePercentMember" xlink:label="smhi_InterestRateSwapAgreementThreePointOneNineFivePercentMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EquityMethodInvestmentOwnershipPercentage" xlink:label="us-gaap_EquityMethodInvestmentOwnershipPercentage"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_MinimumMember" xlink:label="srt_MinimumMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_SEACOR88888Member" xlink:label="smhi_SEACOR88888Member"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_InterestRateSwapMember" xlink:label="us-gaap_InterestRateSwapMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DerivativeFixedInterestRate" xlink:label="us-gaap_DerivativeFixedInterestRate"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_WindcatWorkboatsLtdMember" xlink:label="smhi_WindcatWorkboatsLtdMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ForeignExchangeForwardMember" xlink:label="us-gaap_ForeignExchangeForwardMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_DerivativesNotionalAmount" xlink:label="smhi_DerivativesNotionalAmount"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DerivativeNumberOfInstrumentsHeld" xlink:label="us-gaap_DerivativeNumberOfInstrumentsHeld"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DerivativeFairValueOfDerivativeNet" xlink:label="us-gaap_DerivativeFairValueOfDerivativeNet"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DerivativeCreditRiskValuationAdjustmentDerivativeLiabilities" xlink:label="us-gaap_DerivativeCreditRiskValuationAdjustmentDerivativeLiabilities"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_ProceedsToBeReceivedFromSaleOfBusiness" xlink:label="smhi_ProceedsToBeReceivedFromSaleOfBusiness"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax" xlink:label="us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_DerivativeLineItems" xlink:to="us-gaap_DerivativeTable" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_HedgingRelationshipDomain" xlink:to="us-gaap_FairValueHedgingMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_EquityMethodInvesteeNameDomain" xlink:to="smhi_EquityInvestmentsIn50OrLessOwnedCompaniesMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis" xlink:to="us-gaap_HedgingRelationshipDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_RangeAxis" xlink:to="srt_RangeMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DerivativeContractTypeDomain" xlink:to="smhi_InterestRateSwapAgreementThreePointThreeTwoPercentMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DerivativeLineItems" xlink:to="us-gaap_ChangeInUnrealizedGainLossOnHedgedItemInFairValueHedge1" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DerivativeTable" xlink:to="us-gaap_FairValueByLiabilityClassAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_RangeMember" xlink:to="srt_MaximumMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_FairValueByLiabilityClassAxis" xlink:to="us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_FairValueByLiabilityClassAxis" xlink:to="us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_default" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:to="us-gaap_DerivativeFinancialInstrumentsLiabilitiesMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xlink:to="srt_EquityMethodInvesteeNameDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_HedgingDesignationAxis" xlink:to="us-gaap_HedgingDesignationDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_HedgingDesignationDomain" xlink:to="us-gaap_DesignatedAsHedgingInstrumentMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_EntityDomain" xlink:to="smhi_SEACORMarineForeignHoldingsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_DerivativeInstrumentRiskAxis" xlink:to="us-gaap_DerivativeContractTypeDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_HedgingRelationshipDomain" xlink:to="us-gaap_CashFlowHedgingMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_EquityMethodInvesteeNameDomain" xlink:to="smhi_MexMarMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DerivativeContractTypeDomain" xlink:to="smhi_InterestRateSwapAgreementThreePointOneNineFivePercentMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DerivativeLineItems" xlink:to="us-gaap_EquityMethodInvestmentOwnershipPercentage" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DerivativeTable" xlink:to="us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_RangeMember" xlink:to="srt_MinimumMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_EntityDomain" xlink:to="smhi_SEACOR88888Member" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DerivativeContractTypeDomain" xlink:to="us-gaap_InterestRateSwapMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DerivativeLineItems" xlink:to="us-gaap_DerivativeFixedInterestRate" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DerivativeTable" xlink:to="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_EntityDomain" xlink:to="smhi_WindcatWorkboatsLtdMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DerivativeContractTypeDomain" xlink:to="us-gaap_ForeignExchangeForwardMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DerivativeLineItems" xlink:to="smhi_DerivativesNotionalAmount" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DerivativeTable" xlink:to="srt_RangeAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DerivativeLineItems" xlink:to="us-gaap_DerivativeNumberOfInstrumentsHeld" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DerivativeTable" xlink:to="us-gaap_DerivativeInstrumentRiskAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="5" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DerivativeLineItems" xlink:to="us-gaap_DerivativeFairValueOfDerivativeNet" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="5" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DerivativeTable" xlink:to="us-gaap_HedgingDesignationAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="6" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DerivativeLineItems" xlink:to="us-gaap_DerivativeCreditRiskValuationAdjustmentDerivativeLiabilities" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="6" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DerivativeTable" xlink:to="dei_LegalEntityAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="7" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DerivativeLineItems" xlink:to="smhi_ProceedsToBeReceivedFromSaleOfBusiness" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="8" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DerivativeLineItems" xlink:to="us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax" priority="2" use="optional"/>
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureDerivativeInstrumentsAndHedgingStrategiesEffectOfDerivativeInstrumentsOnOtherComprehensiveIncomeLossDetails">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DerivativeLineItems" xlink:label="us-gaap_DerivativeLineItems"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DerivativeTable" xlink:label="us-gaap_DerivativeTable"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="us-gaap_DerivativeContractTypeDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_InterestRateSwapMember" xlink:label="us-gaap_InterestRateSwapMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax" xlink:label="us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="us-gaap_IncomeStatementLocationAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="us-gaap_IncomeStatementLocationDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_InterestExpenseMember" xlink:label="us-gaap_InterestExpenseMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DerivativeInstrumentRiskAxis" xlink:label="us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_JointVentureInterestRateSwapMember" xlink:label="smhi_JointVentureInterestRateSwapMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax" xlink:label="us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_DerivativeLineItems" xlink:to="us-gaap_DerivativeTable" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DerivativeContractTypeDomain" xlink:to="us-gaap_InterestRateSwapMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DerivativeLineItems" xlink:to="us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DerivativeTable" xlink:to="us-gaap_IncomeStatementLocationAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_IncomeStatementLocationAxis" xlink:to="us-gaap_IncomeStatementLocationDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncomeStatementLocationDomain" xlink:to="us-gaap_InterestExpenseMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_DerivativeInstrumentRiskAxis" xlink:to="us-gaap_DerivativeContractTypeDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DerivativeContractTypeDomain" xlink:to="smhi_JointVentureInterestRateSwapMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DerivativeLineItems" xlink:to="us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DerivativeTable" xlink:to="us-gaap_DerivativeInstrumentRiskAxis" priority="2" use="optional"/>
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureDerivativeInstrumentsAndHedgingStrategiesScheduleOfGainsLossesOnDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsDetails">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DerivativeLineItems" xlink:label="us-gaap_DerivativeLineItems"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DerivativeTable" xlink:label="us-gaap_DerivativeTable"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="us-gaap_DerivativeContractTypeDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EmbeddedDerivativeFinancialInstrumentsMember" xlink:label="us-gaap_EmbeddedDerivativeFinancialInstrumentsMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet" xlink:label="us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DerivativeInstrumentRiskAxis" xlink:label="us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ForeignExchangeOptionMember" xlink:label="us-gaap_ForeignExchangeOptionMember"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_DerivativeLineItems" xlink:to="us-gaap_DerivativeTable" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DerivativeContractTypeDomain" xlink:to="us-gaap_EmbeddedDerivativeFinancialInstrumentsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DerivativeLineItems" xlink:to="us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_DerivativeTable" xlink:to="us-gaap_DerivativeInstrumentRiskAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_DerivativeInstrumentRiskAxis" xlink:to="us-gaap_DerivativeContractTypeDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DerivativeContractTypeDomain" xlink:to="us-gaap_ForeignExchangeOptionMember" priority="2" use="optional"/>
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureFairValueMeasurementsScheduleOfFairValueOfAssetsAndLiabilitiesMeasuredOnRecurringBasisDetails">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:label="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" xlink:label="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="us-gaap_FairValueMeasurementsFairValueHierarchyDomain_default"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DerivativeAssets" xlink:label="us-gaap_DerivativeAssets"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueByMeasurementFrequencyAxis" xlink:label="us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="us-gaap_FairValueMeasurementFrequencyDomain_default"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueInputsLevel1Member" xlink:label="us-gaap_FairValueInputsLevel1Member"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueMeasurementsRecurringMember" xlink:label="us-gaap_FairValueMeasurementsRecurringMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DerivativeAssetStatementOfFinancialPositionExtensibleEnumeration" xlink:label="us-gaap_DerivativeAssetStatementOfFinancialPositionExtensibleEnumeration"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueInputsLevel2Member" xlink:label="us-gaap_FairValueInputsLevel2Member"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DerivativeLiabilities" xlink:label="us-gaap_DerivativeLiabilities"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueInputsLevel3Member" xlink:label="us-gaap_FairValueInputsLevel3Member"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DerivativeLiabilityStatementOfFinancialPositionExtensibleEnumeration" xlink:label="us-gaap_DerivativeLiabilityStatementOfFinancialPositionExtensibleEnumeration"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:to="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:to="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:to="us-gaap_FairValueMeasurementsFairValueHierarchyDomain_default" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:to="us-gaap_DerivativeAssets" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" xlink:to="us-gaap_FairValueByFairValueHierarchyLevelAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_FairValueByMeasurementFrequencyAxis" xlink:to="us-gaap_FairValueMeasurementFrequencyDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_FairValueByMeasurementFrequencyAxis" xlink:to="us-gaap_FairValueMeasurementFrequencyDomain_default" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:to="us-gaap_FairValueInputsLevel1Member" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueMeasurementFrequencyDomain" xlink:to="us-gaap_FairValueMeasurementsRecurringMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:to="us-gaap_DerivativeAssetStatementOfFinancialPositionExtensibleEnumeration" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" xlink:to="us-gaap_FairValueByMeasurementFrequencyAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:to="us-gaap_FairValueInputsLevel2Member" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:to="us-gaap_DerivativeLiabilities" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:to="us-gaap_FairValueInputsLevel3Member" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:to="us-gaap_DerivativeLiabilityStatementOfFinancialPositionExtensibleEnumeration" priority="2" use="optional"/>
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureFairValueMeasurementsScheduleOfEstimatedFairValuesOfFinancialAssetsAndLiabilitiesDetails">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems" xlink:label="us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueByBalanceSheetGroupingTable" xlink:label="us-gaap_FairValueByBalanceSheetGroupingTable"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueDisclosureItemAmountsDomain" xlink:label="us-gaap_FairValueDisclosureItemAmountsDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember" xlink:label="us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueByMeasurementBasisAxis" xlink:label="us-gaap_FairValueByMeasurementBasisAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CashAndCashEquivalentsFairValueDisclosure" xlink:label="us-gaap_CashAndCashEquivalentsFairValueDisclosure"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueInputsLevel1Member" xlink:label="us-gaap_FairValueInputsLevel1Member"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember" xlink:label="us-gaap_PortionAtFairValueFairValueDisclosureMember_default"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CarryingReportedAmountFairValueDisclosureMember" xlink:label="us-gaap_CarryingReportedAmountFairValueDisclosureMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LongTermDebtFairValue" xlink:label="us-gaap_LongTermDebtFairValue"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueInputsLevel2Member" xlink:label="us-gaap_FairValueInputsLevel2Member"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EstimateOfFairValueFairValueDisclosureMember" xlink:label="us-gaap_EstimateOfFairValueFairValueDisclosureMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueInputsLevel3Member" xlink:label="us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems" xlink:to="us-gaap_FairValueByBalanceSheetGroupingTable" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueDisclosureItemAmountsDomain" xlink:to="us-gaap_PortionAtFairValueFairValueDisclosureMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:to="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_FairValueByBalanceSheetGroupingTable" xlink:to="us-gaap_FairValueByMeasurementBasisAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems" xlink:to="us-gaap_CashAndCashEquivalentsFairValueDisclosure" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:to="us-gaap_FairValueInputsLevel1Member" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_FairValueByMeasurementBasisAxis" xlink:to="us-gaap_FairValueDisclosureItemAmountsDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_FairValueByMeasurementBasisAxis" xlink:to="us-gaap_PortionAtFairValueFairValueDisclosureMember_default" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueDisclosureItemAmountsDomain" xlink:to="us-gaap_CarryingReportedAmountFairValueDisclosureMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_FairValueByBalanceSheetGroupingTable" xlink:to="us-gaap_FairValueByFairValueHierarchyLevelAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems" xlink:to="us-gaap_LongTermDebtFairValue" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:to="us-gaap_FairValueInputsLevel2Member" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueDisclosureItemAmountsDomain" xlink:to="us-gaap_EstimateOfFairValueFairValueDisclosureMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:to="us-gaap_FairValueInputsLevel3Member" priority="2" use="optional"/>
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureFairValueMeasurementsAdditionalInformationDetails">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems" xlink:label="us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueByBalanceSheetGroupingTable" xlink:label="us-gaap_FairValueByBalanceSheetGroupingTable"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ImpairedLongLivedAssetsHeldAndUsedByTypeAxis" xlink:label="us-gaap_ImpairedLongLivedAssetsHeldAndUsedByTypeAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ImpairedLongLivedAssetsHeldAndUsedAssetNameDomain" xlink:label="us-gaap_ImpairedLongLivedAssetsHeldAndUsedAssetNameDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_EquityMethodInvesteeNameDomain" xlink:label="srt_EquityMethodInvesteeNameDomain"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_SeabulkTimsIAndOffshoreVesselHoldingsMember" xlink:label="smhi_SeabulkTimsIAndOffshoreVesselHoldingsMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_FastSupportVesselMember" xlink:label="smhi_FastSupportVesselMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="us-gaap_StatementEquityComponentsAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EquityComponentDomain" xlink:label="us-gaap_EquityComponentDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xlink:label="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_NoncontrollingInterestMember" xlink:label="us-gaap_NoncontrollingInterestMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AssetImpairmentCharges" xlink:label="us-gaap_AssetImpairmentCharges"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:label="us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_FairValueInputsLevel2Member" xlink:label="us-gaap_FairValueInputsLevel2Member"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_LiftboatsMember" xlink:label="smhi_LiftboatsMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_MEXMAROffshoreMember" xlink:label="smhi_MEXMAROffshoreMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_AnchorHandlingTowingSupplyVesselMember" xlink:label="smhi_AnchorHandlingTowingSupplyVesselMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ImpairmentOfLongLivedAssetsToBeDisposedOf" xlink:label="us-gaap_ImpairmentOfLongLivedAssetsToBeDisposedOf"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_TowerAndGangwayMember" xlink:label="smhi_TowerAndGangwayMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_NumberOfPropertyAndEquipmentWithFairValue" xlink:label="smhi_NumberOfPropertyAndEquipmentWithFairValue"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ImpairmentOfLongLivedAssetsHeldForUse" xlink:label="us-gaap_ImpairmentOfLongLivedAssetsHeldForUse"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentFairValueDisclosure" xlink:label="us-gaap_PropertyPlantAndEquipmentFairValueDisclosure"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_NumberOfInvestmentsAtEquityInFiftyPercentOrLessOwnedCompaniesMarkedZeroDueToReturnOfFundsThatExceededTheCarryingValueInvestmentAndContinuedLosses" xlink:label="smhi_NumberOfInvestmentsAtEquityInFiftyPercentOrLessOwnedCompaniesMarkedZeroDueToReturnOfFundsThatExceededTheCarryingValueInvestmentAndContinuedLosses"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EquityMethodInvestments" xlink:label="us-gaap_EquityMethodInvestments"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_InvestmentOwnedAtFairValue" xlink:label="us-gaap_InvestmentOwnedAtFairValue"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_InvestmentOwnedExcessAmountFairValue" xlink:label="smhi_InvestmentOwnedExcessAmountFairValue"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_InvestmentOwnedBalancePrincipalAmount" xlink:label="us-gaap_InvestmentOwnedBalancePrincipalAmount"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems" xlink:to="us-gaap_FairValueByBalanceSheetGroupingTable" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_ImpairedLongLivedAssetsHeldAndUsedByTypeAxis" xlink:to="us-gaap_ImpairedLongLivedAssetsHeldAndUsedAssetNameDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_EquityMethodInvesteeNameDomain" xlink:to="smhi_SeabulkTimsIAndOffshoreVesselHoldingsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ImpairedLongLivedAssetsHeldAndUsedAssetNameDomain" xlink:to="smhi_FastSupportVesselMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:to="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementEquityComponentsAxis" xlink:to="us-gaap_EquityComponentDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xlink:to="srt_EquityMethodInvesteeNameDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_NoncontrollingInterestMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_FairValueByBalanceSheetGroupingTable" xlink:to="us-gaap_FairValueByFairValueHierarchyLevelAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems" xlink:to="us-gaap_AssetImpairmentCharges" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:to="us-gaap_PropertyPlantAndEquipmentTypeDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:to="us-gaap_FairValueInputsLevel2Member" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="smhi_LiftboatsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_EquityMethodInvesteeNameDomain" xlink:to="smhi_MEXMAROffshoreMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ImpairedLongLivedAssetsHeldAndUsedAssetNameDomain" xlink:to="smhi_AnchorHandlingTowingSupplyVesselMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_FairValueByBalanceSheetGroupingTable" xlink:to="us-gaap_PropertyPlantAndEquipmentByTypeAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems" xlink:to="us-gaap_ImpairmentOfLongLivedAssetsToBeDisposedOf" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ImpairedLongLivedAssetsHeldAndUsedAssetNameDomain" xlink:to="smhi_TowerAndGangwayMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_FairValueByBalanceSheetGroupingTable" xlink:to="us-gaap_StatementEquityComponentsAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems" xlink:to="smhi_NumberOfPropertyAndEquipmentWithFairValue" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_FairValueByBalanceSheetGroupingTable" xlink:to="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems" xlink:to="us-gaap_ImpairmentOfLongLivedAssetsHeldForUse" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_FairValueByBalanceSheetGroupingTable" xlink:to="us-gaap_ImpairedLongLivedAssetsHeldAndUsedByTypeAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems" xlink:to="us-gaap_PropertyPlantAndEquipmentFairValueDisclosure" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="5" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems" xlink:to="smhi_NumberOfInvestmentsAtEquityInFiftyPercentOrLessOwnedCompaniesMarkedZeroDueToReturnOfFundsThatExceededTheCarryingValueInvestmentAndContinuedLosses" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="6" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems" xlink:to="us-gaap_EquityMethodInvestments" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="7" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems" xlink:to="us-gaap_InvestmentOwnedAtFairValue" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="8" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems" xlink:to="smhi_InvestmentOwnedExcessAmountFairValue" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="9" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems" xlink:to="us-gaap_InvestmentOwnedBalancePrincipalAmount" priority="2" use="optional"/>
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureWarrantsAdditionalInformationDetails">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfWarrantOrRightLineItems" xlink:label="us-gaap_ClassOfWarrantOrRightLineItems"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfWarrantOrRightTable" xlink:label="us-gaap_ClassOfWarrantOrRightTable"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfWarrantOrRightAxis" xlink:label="us-gaap_ClassOfWarrantOrRightAxis"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_ClassOfWarrantOrRightExercisedDuringPeriod" xlink:label="smhi_ClassOfWarrantOrRightExercisedDuringPeriod"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfWarrantOrRightDomain" xlink:label="us-gaap_ClassOfWarrantOrRightDomain"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_WarrantsTransactionsMember" xlink:label="smhi_WarrantsTransactionsMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1" xlink:label="us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights" xlink:label="us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfWarrantOrRightOutstanding" xlink:label="us-gaap_ClassOfWarrantOrRightOutstanding"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_StockIssuedDuringPeriodSharesWarrantsExercisedSharesWithHeldAsPaymentOfExercise" xlink:label="smhi_StockIssuedDuringPeriodSharesWarrantsExercisedSharesWithHeldAsPaymentOfExercise"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_ClassOfWarrantOrRightLineItems" xlink:to="us-gaap_ClassOfWarrantOrRightTable" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ClassOfWarrantOrRightTable" xlink:to="us-gaap_ClassOfWarrantOrRightAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfWarrantOrRightLineItems" xlink:to="smhi_ClassOfWarrantOrRightExercisedDuringPeriod" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfWarrantOrRightDomain" xlink:to="smhi_WarrantsTransactionsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_ClassOfWarrantOrRightAxis" xlink:to="us-gaap_ClassOfWarrantOrRightDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfWarrantOrRightLineItems" xlink:to="us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfWarrantOrRightLineItems" xlink:to="us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfWarrantOrRightLineItems" xlink:to="us-gaap_ClassOfWarrantOrRightOutstanding" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfWarrantOrRightLineItems" xlink:to="smhi_StockIssuedDuringPeriodSharesWarrantsExercisedSharesWithHeldAsPaymentOfExercise" priority="2" use="optional"/>
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureStockholdersEquityAdditionalInformationDetails">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfStockLineItems" xlink:label="us-gaap_ClassOfStockLineItems"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfStockByClassTable" xlink:label="us-gaap_ScheduleOfStockByClassTable"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="us-gaap_BusinessAcquisitionAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PlanNameDomain" xlink:label="us-gaap_PlanNameDomain"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_TwoThousandSeventeenEquityIncentivePlanMember" xlink:label="smhi_TwoThousandSeventeenEquityIncentivePlanMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SaleOfStockNameOfTransactionDomain" xlink:label="us-gaap_SaleOfStockNameOfTransactionDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PrivatePlacementMember" xlink:label="us-gaap_PrivatePlacementMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_MergerAgreementMember" xlink:label="smhi_MergerAgreementMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_CumulativeEffectPeriodOfAdoptionAxis" xlink:label="srt_CumulativeEffectPeriodOfAdoptionAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_CumulativeEffectPeriodOfAdoptionDomain" xlink:label="srt_CumulativeEffectPeriodOfAdoptionDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_EquityMethodInvesteeNameDomain" xlink:label="srt_EquityMethodInvesteeNameDomain"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_OSVPartnersMember" xlink:label="smhi_OSVPartnersMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TypeOfArrangementAxis" xlink:label="us-gaap_TypeOfArrangementAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="us-gaap_ArrangementsAndNonarrangementTransactionsMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SubsidiarySaleOfStockAxis" xlink:label="us-gaap_SubsidiarySaleOfStockAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SaleOfStockNameOfTransactionDomain" xlink:label="us-gaap_SaleOfStockNameOfTransactionDomain_default"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfWarrantOrRightDomain" xlink:label="us-gaap_ClassOfWarrantOrRightDomain"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_ExchangeWarrantsMember" xlink:label="smhi_ExchangeWarrantsMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember" xlink:label="srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="us-gaap_StatementEquityComponentsAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EquityComponentDomain" xlink:label="us-gaap_EquityComponentDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TypeOfAdoptionMember" xlink:label="us-gaap_TypeOfAdoptionMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AccountingStandardsUpdate201602Member" xlink:label="us-gaap_AccountingStandardsUpdate201602Member"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PartnerTypeOfPartnersCapitalAccountAxis" xlink:label="us-gaap_PartnerTypeOfPartnersCapitalAccountAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PartnerTypeOfPartnersCapitalAccountNameDomain" xlink:label="us-gaap_PartnerTypeOfPartnersCapitalAccountNameDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xlink:label="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_MergerConsiderationMember" xlink:label="smhi_MergerConsiderationMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EquityInterestIssuedOrIssuableTypeDomain" xlink:label="us-gaap_EquityInterestIssuedOrIssuableTypeDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommonStockMember" xlink:label="us-gaap_CommonStockMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RetainedEarningsMember" xlink:label="us-gaap_RetainedEarningsMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued" xlink:label="us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EquityInterestIssuedOrIssuableByTypeAxis" xlink:label="us-gaap_EquityInterestIssuedOrIssuableByTypeAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" xlink:label="us-gaap_AdjustmentsForNewAccountingPronouncementsAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfWarrantOrRightAxis" xlink:label="us-gaap_ClassOfWarrantOrRightAxis"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_SeabulkOverseasMember" xlink:label="smhi_SeabulkOverseasMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LimitedPartnerMember" xlink:label="us-gaap_LimitedPartnerMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PlanNameAxis" xlink:label="us-gaap_PlanNameAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PlanNameDomain" xlink:label="us-gaap_PlanNameDomain_default"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_TwoThousandTwentyEquityIncentivePlanMember" xlink:label="smhi_TwoThousandTwentyEquityIncentivePlanMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_WindcatWorkboatsFacilitiesMember" xlink:label="smhi_WindcatWorkboatsFacilitiesMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_OSVPartnersOneMember" xlink:label="smhi_OSVPartnersOneMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_PaymentInKindPIKLoanMember" xlink:label="smhi_PaymentInKindPIKLoanMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_ClassOfWarrantOrRightExercisedDuringPeriod" xlink:label="smhi_ClassOfWarrantOrRightExercisedDuringPeriod"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_FalconGlobalHoldingMember" xlink:label="smhi_FalconGlobalHoldingMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfWarrantOrRightOutstanding" xlink:label="us-gaap_ClassOfWarrantOrRightOutstanding"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_StockIssuedDuringPeriodSharesWarrantsExercisedSharesWithHeldAsPaymentOfExercise" xlink:label="smhi_StockIssuedDuringPeriodSharesWarrantsExercisedSharesWithHeldAsPaymentOfExercise"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommonStockCapitalSharesReservedForFutureIssuance" xlink:label="us-gaap_CommonStockCapitalSharesReservedForFutureIssuance"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired" xlink:label="us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_MinorityInterestOwnershipPercentageByParent" xlink:label="us-gaap_MinorityInterestOwnershipPercentageByParent"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_BusinessCombinationConsiderationTransferred1" xlink:label="us-gaap_BusinessCombinationConsiderationTransferred1"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:label="us-gaap_StockIssuedDuringPeriodSharesNewIssues"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_NumberOfEquipmentAcquired" xlink:label="smhi_NumberOfEquipmentAcquired"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommonStockValue" xlink:label="us-gaap_CommonStockValue"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" xlink:label="us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_ClassOfStockLineItems" xlink:to="us-gaap_ScheduleOfStockByClassTable" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_BusinessAcquisitionAxis" xlink:to="us-gaap_BusinessAcquisitionAcquireeDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PlanNameDomain" xlink:to="smhi_TwoThousandSeventeenEquityIncentivePlanMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SaleOfStockNameOfTransactionDomain" xlink:to="us-gaap_PrivatePlacementMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_BusinessAcquisitionAcquireeDomain" xlink:to="smhi_MergerAgreementMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_CumulativeEffectPeriodOfAdoptionAxis" xlink:to="srt_CumulativeEffectPeriodOfAdoptionDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_EquityMethodInvesteeNameDomain" xlink:to="smhi_OSVPartnersMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_TypeOfArrangementAxis" xlink:to="us-gaap_ArrangementsAndNonarrangementTransactionsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_SubsidiarySaleOfStockAxis" xlink:to="us-gaap_SaleOfStockNameOfTransactionDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_SubsidiarySaleOfStockAxis" xlink:to="us-gaap_SaleOfStockNameOfTransactionDomain_default" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfWarrantOrRightDomain" xlink:to="smhi_ExchangeWarrantsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_CumulativeEffectPeriodOfAdoptionDomain" xlink:to="srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementEquityComponentsAxis" xlink:to="us-gaap_EquityComponentDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_TypeOfAdoptionMember" xlink:to="us-gaap_AccountingStandardsUpdate201602Member" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_PartnerTypeOfPartnersCapitalAccountAxis" xlink:to="us-gaap_PartnerTypeOfPartnersCapitalAccountNameDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfStockByClassTable" xlink:to="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xlink:to="srt_EquityMethodInvesteeNameDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:to="smhi_MergerConsiderationMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityInterestIssuedOrIssuableTypeDomain" xlink:to="us-gaap_CommonStockMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_RetainedEarningsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockLineItems" xlink:to="us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_EquityInterestIssuedOrIssuableByTypeAxis" xlink:to="us-gaap_EquityInterestIssuedOrIssuableTypeDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" xlink:to="us-gaap_TypeOfAdoptionMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_ClassOfWarrantOrRightAxis" xlink:to="us-gaap_ClassOfWarrantOrRightDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_EntityDomain" xlink:to="smhi_SeabulkOverseasMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PartnerTypeOfPartnersCapitalAccountNameDomain" xlink:to="us-gaap_LimitedPartnerMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_PlanNameAxis" xlink:to="us-gaap_PlanNameDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_PlanNameAxis" xlink:to="us-gaap_PlanNameDomain_default" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PlanNameDomain" xlink:to="smhi_TwoThousandTwentyEquityIncentivePlanMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_BusinessAcquisitionAcquireeDomain" xlink:to="smhi_WindcatWorkboatsFacilitiesMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_EquityMethodInvesteeNameDomain" xlink:to="smhi_OSVPartnersOneMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfStockByClassTable" xlink:to="us-gaap_BusinessAcquisitionAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:to="smhi_PaymentInKindPIKLoanMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockLineItems" xlink:to="smhi_ClassOfWarrantOrRightExercisedDuringPeriod" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_BusinessAcquisitionAcquireeDomain" xlink:to="smhi_FalconGlobalHoldingMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfStockByClassTable" xlink:to="us-gaap_EquityInterestIssuedOrIssuableByTypeAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockLineItems" xlink:to="us-gaap_ClassOfWarrantOrRightOutstanding" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfStockByClassTable" xlink:to="us-gaap_TypeOfArrangementAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockLineItems" xlink:to="smhi_StockIssuedDuringPeriodSharesWarrantsExercisedSharesWithHeldAsPaymentOfExercise" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfStockByClassTable" xlink:to="us-gaap_PartnerTypeOfPartnersCapitalAccountAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockLineItems" xlink:to="us-gaap_CommonStockCapitalSharesReservedForFutureIssuance" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="5" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfStockByClassTable" xlink:to="us-gaap_ClassOfWarrantOrRightAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="5" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="6" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfStockByClassTable" xlink:to="us-gaap_PlanNameAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="6" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="7" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfStockByClassTable" xlink:to="dei_LegalEntityAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="7" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockLineItems" xlink:to="us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="8" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfStockByClassTable" xlink:to="us-gaap_SubsidiarySaleOfStockAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="8" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockLineItems" xlink:to="us-gaap_MinorityInterestOwnershipPercentageByParent" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="9" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfStockByClassTable" xlink:to="us-gaap_StatementEquityComponentsAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="9" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockLineItems" xlink:to="us-gaap_BusinessCombinationConsiderationTransferred1" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="10" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfStockByClassTable" xlink:to="us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="10" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockLineItems" xlink:to="us-gaap_StockIssuedDuringPeriodSharesNewIssues" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="11" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfStockByClassTable" xlink:to="srt_CumulativeEffectPeriodOfAdoptionAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="11" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockLineItems" xlink:to="smhi_NumberOfEquipmentAcquired" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="12" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockLineItems" xlink:to="us-gaap_CommonStockValue" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="13" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockLineItems" xlink:to="us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" priority="2" use="optional"/>
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureNoncontrollingInterestsInSubsidiariesScheduleOfNoncontrollingInterestsInCompanySConsolidatedSubsidiariesDetails">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_MinorityInterestLineItems" xlink:label="us-gaap_MinorityInterestLineItems"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_MinorityInterestTable" xlink:label="us-gaap_MinorityInterestTable"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners" xlink:label="us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_OwnershipDomain" xlink:label="srt_OwnershipDomain"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_VEESEAHoldingsIncMember" xlink:label="smhi_VEESEAHoldingsIncMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_OwnershipAxis" xlink:label="srt_OwnershipAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_MinorityInterest" xlink:label="us-gaap_MinorityInterest"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_MinorityInterestLineItems" xlink:to="us-gaap_MinorityInterestTable" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_MinorityInterestLineItems" xlink:to="us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_OwnershipDomain" xlink:to="smhi_VEESEAHoldingsIncMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_MinorityInterestTable" xlink:to="srt_OwnershipAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_OwnershipAxis" xlink:to="srt_OwnershipDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_MinorityInterestLineItems" xlink:to="us-gaap_MinorityInterest" priority="2" use="optional"/>
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureSavingsAndMultiEmployerPensionPlansAdditionalInformationDetails">
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_PensionAndOtherPostretirementBenefitsDisclosureLineItems" xlink:label="smhi_PensionAndOtherPostretirementBenefitsDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_PensionAndOtherPostretirementBenefitsDisclosureTable" xlink:label="smhi_PensionAndOtherPostretirementBenefitsDisclosureTable"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RetirementPlanTypeAxis" xlink:label="us-gaap_RetirementPlanTypeAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RetirementPlanTypeDomain" xlink:label="us-gaap_RetirementPlanTypeDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RetirementPlanTypeDomain" xlink:label="us-gaap_RetirementPlanTypeDomain_default"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_OtherDefinedContributionPlanMember" xlink:label="smhi_OtherDefinedContributionPlanMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent" xlink:label="us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DefinedContributionPlanMaximumAnnualContributionsPerEmployeeAmount" xlink:label="us-gaap_DefinedContributionPlanMaximumAnnualContributionsPerEmployeeAmount"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DefinedContributionPlanCostRecognized" xlink:label="us-gaap_DefinedContributionPlanCostRecognized"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="smhi_PensionAndOtherPostretirementBenefitsDisclosureLineItems" xlink:to="smhi_PensionAndOtherPostretirementBenefitsDisclosureTable" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_RetirementPlanTypeAxis" xlink:to="us-gaap_RetirementPlanTypeDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_RetirementPlanTypeAxis" xlink:to="us-gaap_RetirementPlanTypeDomain_default" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="smhi_PensionAndOtherPostretirementBenefitsDisclosureTable" xlink:to="us-gaap_RetirementPlanTypeAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RetirementPlanTypeDomain" xlink:to="smhi_OtherDefinedContributionPlanMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_PensionAndOtherPostretirementBenefitsDisclosureLineItems" xlink:to="us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_PensionAndOtherPostretirementBenefitsDisclosureLineItems" xlink:to="us-gaap_DefinedContributionPlanMaximumAnnualContributionsPerEmployeeAmount" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_PensionAndOtherPostretirementBenefitsDisclosureLineItems" xlink:to="us-gaap_DefinedContributionPlanCostRecognized" priority="2" use="optional"/>
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureShareBasedCompensationAdditionalInformationDetails">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PlanNameDomain" xlink:label="us-gaap_PlanNameDomain"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_EquityIncentivePlan2017Member" xlink:label="smhi_EquityIncentivePlan2017Member"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeAxis" xlink:label="srt_RangeAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeMember" xlink:label="srt_RangeMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_MinimumMember" xlink:label="srt_MinimumMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RestrictedStockMember" xlink:label="us-gaap_RestrictedStockMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AwardTypeAxis" xlink:label="us-gaap_AwardTypeAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PlanNameAxis" xlink:label="us-gaap_PlanNameAxis"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_TwoThousandTwentyEquityIncentivePlanMember" xlink:label="smhi_TwoThousandTwentyEquityIncentivePlanMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_MaximumMember" xlink:label="srt_MaximumMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EmployeeStockOptionMember" xlink:label="us-gaap_EmployeeStockOptionMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_EquityIncentivePlan2017And2020Member" xlink:label="smhi_EquityIncentivePlan2017And2020Member"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_PerformanceRestrictedStockUnitsMember" xlink:label="smhi_PerformanceRestrictedStockUnitsMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommonStockCapitalSharesReservedForFutureIssuance" xlink:label="us-gaap_CommonStockCapitalSharesReservedForFutureIssuance"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_EmployeeStockPurchasePlanMember" xlink:label="smhi_EmployeeStockPurchasePlanMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_PercentageOfNumberOfCommonStockSharesOutstanding" xlink:label="smhi_PercentageOfNumberOfCommonStockSharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_TwoThousandSeventeenAndTwoThousandTwentyPlanMember" xlink:label="smhi_TwoThousandSeventeenAndTwoThousandTwentyPlanMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_TwoThousandTwentyTwoEquityIncentivePlanMember" xlink:label="smhi_TwoThousandTwentyTwoEquityIncentivePlanMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_PaymentsForDistributionOfRestrictedStockSpinOff" xlink:label="smhi_PaymentsForDistributionOfRestrictedStockSpinOff"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_TwoThousandSeventeenTwoThousandTwentyAndTwoThousandTwentyTwoEquityIncentivePlanMember" xlink:label="smhi_TwoThousandSeventeenTwoThousandTwentyAndTwoThousandTwentyTwoEquityIncentivePlanMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_DistributionOfRestrictedStockInConnectionWithSpinoff" xlink:label="smhi_DistributionOfRestrictedStockInConnectionWithSpinoff"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardDiscountFromMarketPricePurchaseDate" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardDiscountFromMarketPricePurchaseDate"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AllocatedShareBasedCompensationExpense" xlink:label="us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsDiscountForPostvestingRestrictions" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsDiscountForPostvestingRestrictions"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" xlink:label="us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PlanNameDomain" xlink:to="smhi_EquityIncentivePlan2017Member" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_RangeAxis" xlink:to="srt_RangeMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_RangeMember" xlink:to="srt_MinimumMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="us-gaap_RestrictedStockMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_AwardTypeAxis" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="us-gaap_PlanNameAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_PlanNameAxis" xlink:to="us-gaap_PlanNameDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PlanNameDomain" xlink:to="smhi_TwoThousandTwentyEquityIncentivePlanMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_RangeMember" xlink:to="srt_MaximumMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="us-gaap_EmployeeStockOptionMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="us-gaap_AwardTypeAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PlanNameDomain" xlink:to="smhi_EquityIncentivePlan2017And2020Member" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="smhi_PerformanceRestrictedStockUnitsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_CommonStockCapitalSharesReservedForFutureIssuance" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="srt_RangeAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PlanNameDomain" xlink:to="smhi_EmployeeStockPurchasePlanMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="smhi_PercentageOfNumberOfCommonStockSharesOutstanding" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PlanNameDomain" xlink:to="smhi_TwoThousandSeventeenAndTwoThousandTwentyPlanMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="5" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PlanNameDomain" xlink:to="smhi_TwoThousandTwentyTwoEquityIncentivePlanMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="5" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="smhi_PaymentsForDistributionOfRestrictedStockSpinOff" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="6" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PlanNameDomain" xlink:to="smhi_TwoThousandSeventeenTwoThousandTwentyAndTwoThousandTwentyTwoEquityIncentivePlanMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="6" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="smhi_DistributionOfRestrictedStockInConnectionWithSpinoff" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="7" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardDiscountFromMarketPricePurchaseDate" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="8" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="9" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_AllocatedShareBasedCompensationExpense" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="10" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="11" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="12" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="13" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="14" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="15" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="16" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="17" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsDiscountForPostvestingRestrictions" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="18" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="19" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" priority="2" use="optional"/>
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureShareBasedCompensationScheduleOfEquityIncentivePlanTransactionsDetails">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_DirectorStockAwardsMember" xlink:label="smhi_DirectorStockAwardsMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AwardTypeAxis" xlink:label="us-gaap_AwardTypeAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RestrictedStockMember" xlink:label="us-gaap_RestrictedStockMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" xlink:label="us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="smhi_DirectorStockAwardsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_AwardTypeAxis" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="us-gaap_AwardTypeAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="us-gaap_RestrictedStockMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="5" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="6" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="7" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="8" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod" priority="2" use="optional"/>
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureShareBasedCompensationScheduleOfEquityIncentivePlanTransactionsDetailsParenthetical">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeAxis" xlink:label="srt_RangeAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeMember" xlink:label="srt_RangeMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_MaximumMember" xlink:label="srt_MaximumMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PerformanceSharesMember" xlink:label="us-gaap_PerformanceSharesMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AwardTypeAxis" xlink:label="us-gaap_AwardTypeAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriodBeforeAdjustment" xlink:label="smhi_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriodBeforeAdjustment"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPreviousPeriodGross" xlink:label="smhi_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPreviousPeriodGross"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_RangeAxis" xlink:to="srt_RangeMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_RangeMember" xlink:to="srt_MaximumMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="us-gaap_PerformanceSharesMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_AwardTypeAxis" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="us-gaap_AwardTypeAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="srt_RangeAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="smhi_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriodBeforeAdjustment" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="smhi_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPreviousPeriodGross" priority="2" use="optional"/>
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureShareBasedCompensationScheduleOfRestrictedStockTransactionsDetails">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RestrictedStockMember" xlink:label="us-gaap_RestrictedStockMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AwardTypeAxis" xlink:label="us-gaap_AwardTypeAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="us-gaap_RestrictedStockMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_AwardTypeAxis" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="us-gaap_AwardTypeAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="5" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="6" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="7" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue" priority="2" use="optional"/>
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureRelatedPartyTransactionsAdditionalInformationDetails">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RelatedPartyTransactionLineItems" xlink:label="us-gaap_RelatedPartyTransactionLineItems"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable" xlink:label="us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="us-gaap_BusinessAcquisitionAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SaleOfStockNameOfTransactionDomain" xlink:label="us-gaap_SaleOfStockNameOfTransactionDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PrivatePlacementMember" xlink:label="us-gaap_PrivatePlacementMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_ExchangeMember" xlink:label="smhi_ExchangeMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_EquityMethodInvesteeNameDomain" xlink:label="srt_EquityMethodInvesteeNameDomain"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_OSVPartnersMember" xlink:label="smhi_OSVPartnersMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_TypeOfArrangementAxis" xlink:label="us-gaap_TypeOfArrangementAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="us-gaap_ArrangementsAndNonarrangementTransactionsMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentRedemptionPeriodDomain" xlink:label="us-gaap_DebtInstrumentRedemptionPeriodDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentRedemptionPeriodOneMember" xlink:label="us-gaap_DebtInstrumentRedemptionPeriodOneMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeAxis" xlink:label="srt_RangeAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeMember" xlink:label="srt_RangeMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:label="us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RelatedPartyDomain" xlink:label="us-gaap_RelatedPartyDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RelatedPartyDomain" xlink:label="us-gaap_RelatedPartyDomain_default"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RepurchaseAgreementCounterpartyNameDomain" xlink:label="srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_CarolineMember" xlink:label="smhi_CarolineMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_SegmentGeographicalDomain" xlink:label="srt_SegmentGeographicalDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/country/2022/country-2022.xsd#country_BR" xlink:label="country_BR"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_MaximumMember" xlink:label="srt_MaximumMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SubsidiarySaleOfStockAxis" xlink:label="us-gaap_SubsidiarySaleOfStockAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfStockDomain" xlink:label="us-gaap_ClassOfStockDomain"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_PreferredInterestsAndClassAPreferredInterestsMember" xlink:label="smhi_PreferredInterestsAndClassAPreferredInterestsMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2022/dei-2022.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LongtermDebtTypeAxis" xlink:label="us-gaap_LongtermDebtTypeAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="us-gaap_LongtermDebtTypeDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CreditFacilityDomain" xlink:label="us-gaap_CreditFacilityDomain"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_OSVCreditFacilityMember" xlink:label="smhi_OSVCreditFacilityMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CreditFacilityAxis" xlink:label="us-gaap_CreditFacilityAxis"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_SEACORHoldingsMember" xlink:label="smhi_SEACORHoldingsMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfWarrantOrRightDomain" xlink:label="us-gaap_ClassOfWarrantOrRightDomain"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_WarrantsIssuedInPrivatePlacementMember" xlink:label="smhi_WarrantsIssuedInPrivatePlacementMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtConversionByUniqueDescriptionAxis" xlink:label="us-gaap_DebtConversionByUniqueDescriptionAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtConversionNameDomain" xlink:label="us-gaap_DebtConversionNameDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RelatedPartyTransactionAxis" xlink:label="us-gaap_RelatedPartyTransactionAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RelatedPartyTransactionDomain" xlink:label="us-gaap_RelatedPartyTransactionDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RelatedPartyTransactionDomain" xlink:label="us-gaap_RelatedPartyTransactionDomain_default"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PartnerTypeOfPartnersCapitalAccountAxis" xlink:label="us-gaap_PartnerTypeOfPartnersCapitalAccountAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PartnerTypeOfPartnersCapitalAccountNameDomain" xlink:label="us-gaap_PartnerTypeOfPartnersCapitalAccountNameDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xlink:label="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_TaxRefundAgreementMember" xlink:label="smhi_TaxRefundAgreementMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="us-gaap_StatementClassOfStockAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfStockDomain" xlink:label="us-gaap_ClassOfStockDomain_default"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EquityInterestIssuedOrIssuableTypeDomain" xlink:label="us-gaap_EquityInterestIssuedOrIssuableTypeDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CommonStockMember" xlink:label="us-gaap_CommonStockMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_OwnershipDomain" xlink:label="srt_OwnershipDomain"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_SubsidiariesOfCMEMember" xlink:label="smhi_SubsidiariesOfCMEMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_StatementGeographicalAxis" xlink:label="srt_StatementGeographicalAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EquityInterestIssuedOrIssuableByTypeAxis" xlink:label="us-gaap_EquityInterestIssuedOrIssuableByTypeAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentAxis" xlink:label="us-gaap_DebtInstrumentAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="us-gaap_DebtInstrumentNameDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_CounterpartyNameAxis" xlink:label="srt_CounterpartyNameAxis"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_TransitionServicesAgreementMember" xlink:label="smhi_TransitionServicesAgreementMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentRedemptionPeriodAxis" xlink:label="us-gaap_DebtInstrumentRedemptionPeriodAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EquityMethodInvestmentNonconsolidatedInvesteeDomain" xlink:label="us-gaap_EquityMethodInvestmentNonconsolidatedInvesteeDomain"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_OPEMMember" xlink:label="smhi_OPEMMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_SeniorPIKToggleNotesDueTwoThousandTwentySixMember" xlink:label="smhi_SeniorPIKToggleNotesDueTwoThousandTwentySixMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfWarrantOrRightAxis" xlink:label="us-gaap_ClassOfWarrantOrRightAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:label="us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_RelatedPartyTransactionsMinimumAmountOfTransactionsForReviewAndApproval" xlink:label="smhi_RelatedPartyTransactionsMinimumAmountOfTransactionsForReviewAndApproval"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_SeabulkOverseasMember" xlink:label="smhi_SeabulkOverseasMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LimitedPartnerMember" xlink:label="us-gaap_LimitedPartnerMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_OwnershipAxis" xlink:label="srt_OwnershipAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="srt_TitleOfIndividualWithRelationshipToEntityDomain"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_NonExecutiveChairmanMember" xlink:label="smhi_NonExecutiveChairmanMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_TitleOfIndividualAxis" xlink:label="srt_TitleOfIndividualAxis"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_PlatformSupplyVesselsMember" xlink:label="smhi_PlatformSupplyVesselsMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EquityMethodInvestmentNonconsolidatedInvesteeAxis" xlink:label="us-gaap_EquityMethodInvestmentNonconsolidatedInvesteeAxis"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_ConvertibleSeniorNotesConvertedToWarrantsMember" xlink:label="smhi_ConvertibleSeniorNotesConvertedToWarrantsMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_CashInterestMember" xlink:label="smhi_CashInterestMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_ThirdPartyLenderMember" xlink:label="smhi_ThirdPartyLenderMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_OSVPartnersOneMember" xlink:label="smhi_OSVPartnersOneMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentRedemptionPeriodTwoMember" xlink:label="us-gaap_DebtInstrumentRedemptionPeriodTwoMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_CarolineIIMember" xlink:label="smhi_CarolineIIMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_MinimumMember" xlink:label="srt_MinimumMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_TermLoanMember" xlink:label="smhi_TermLoanMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_TwoThousandSeventeenPreferredInterestsMember" xlink:label="smhi_TwoThousandSeventeenPreferredInterestsMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_OtherThanCarlyleMember" xlink:label="smhi_OtherThanCarlyleMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_MergerConsiderationMember" xlink:label="smhi_MergerConsiderationMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_SubsidiaryOfMexMarMember" xlink:label="smhi_SubsidiaryOfMexMarMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_ClassAPreferredInterestsMember" xlink:label="smhi_ClassAPreferredInterestsMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_ConvertibleSeniorNotesDueTwoThousandTwentySixMember" xlink:label="smhi_ConvertibleSeniorNotesDueTwoThousandTwentySixMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_GuaranteeObligationsMaximumExposure" xlink:label="us-gaap_GuaranteeObligationsMaximumExposure"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_TalosEnergyIncMember" xlink:label="smhi_TalosEnergyIncMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_PresidentChiefExecutiveOfficerAndDirectorMember" xlink:label="smhi_PresidentChiefExecutiveOfficerAndDirectorMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_HybridInterestMember" xlink:label="smhi_HybridInterestMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_PrincipalMember" xlink:label="smhi_PrincipalMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_MexMarMember" xlink:label="smhi_MexMarMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentRedemptionPeriodThreeMember" xlink:label="us-gaap_DebtInstrumentRedemptionPeriodThreeMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_CarlyleGroupMember" xlink:label="smhi_CarlyleGroupMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_PaymentInKindPIKLoanMember" xlink:label="smhi_PaymentInKindPIKLoanMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_OTMMember" xlink:label="smhi_OTMMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_SecondLienDebtMember" xlink:label="smhi_SecondLienDebtMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_GuaranteedNotesMember" xlink:label="smhi_GuaranteedNotesMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_InterestExpenseRelatedParty" xlink:label="us-gaap_InterestExpenseRelatedParty"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_ExecutiveVicePresidentAndChiefFinancialOfficerMember" xlink:label="smhi_ExecutiveVicePresidentAndChiefFinancialOfficerMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_HybridInterestPaidInCashMember" xlink:label="smhi_HybridInterestPaidInCashMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_MergerAgreementMember" xlink:label="smhi_MergerAgreementMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_MEXMAROffshoreMember" xlink:label="smhi_MEXMAROffshoreMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_MergerConsiderationAndPaymentInKindLoanConsiderationMember" xlink:label="smhi_MergerConsiderationAndPaymentInKindLoanConsiderationMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_OsvPartnerMember" xlink:label="smhi_OsvPartnerMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_ConvertibleSeniorNotesMember" xlink:label="smhi_ConvertibleSeniorNotesMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ProceedsFromIncomeTaxRefunds" xlink:label="us-gaap_ProceedsFromIncomeTaxRefunds"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_HybridInterestPaymentInKindMember" xlink:label="smhi_HybridInterestPaymentInKindMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_WindcatWorkboatsFacilitiesMember" xlink:label="smhi_WindcatWorkboatsFacilitiesMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_ClassAPreferredInterestsCarolineMember" xlink:label="smhi_ClassAPreferredInterestsCarolineMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_PriorToClosingOfFrameworkAgreementMember" xlink:label="smhi_PriorToClosingOfFrameworkAgreementMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_OSVPartnerOneMember" xlink:label="smhi_OSVPartnerOneMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_ConvertibleSeniorNotesDueTwoThousandTwentyThreeMember" xlink:label="smhi_ConvertibleSeniorNotesDueTwoThousandTwentyThreeMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_PercentageOfNetOperatingLossesFacilitateTaxSavings" xlink:label="smhi_PercentageOfNetOperatingLossesFacilitateTaxSavings"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_UPOffshoresMember" xlink:label="smhi_UPOffshoresMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_PIKLoanDebtAndCarolineTwoMember" xlink:label="smhi_PIKLoanDebtAndCarolineTwoMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_MexMarOriginalFacilityAgreementMember" xlink:label="smhi_MexMarOriginalFacilityAgreementMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_InterestReceived" xlink:label="smhi_InterestReceived"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_ClassAPreferredInterestsCarolineTwoMember" xlink:label="smhi_ClassAPreferredInterestsCarolineTwoMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_MexMarSecondAmendedAndRestatedFacilityAgreementMember" xlink:label="smhi_MexMarSecondAmendedAndRestatedFacilityAgreementMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_TransactionFee" xlink:label="smhi_TransactionFee"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_PIKLoanDebtMember" xlink:label="smhi_PIKLoanDebtMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_MexMarThirdAmendedAndRestatedFacilityAgreementMember" xlink:label="smhi_MexMarThirdAmendedAndRestatedFacilityAgreementMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_CashTaxRefundsWithoutRestrictionsToUse" xlink:label="smhi_CashTaxRefundsWithoutRestrictionsToUse"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_CMEMember" xlink:label="smhi_CMEMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_LenderNonRecourseMember" xlink:label="smhi_LenderNonRecourseMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_CashTaxRefundsWithRestrictionsToUse" xlink:label="smhi_CashTaxRefundsWithRestrictionsToUse"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_SEACORMarlinLLCMember" xlink:label="smhi_SEACORMarlinLLCMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_TaxRefundsRestrictedCash" xlink:label="smhi_TaxRefundsRestrictedCash"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_OVHMember" xlink:label="smhi_OVHMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RestrictedCash" xlink:label="us-gaap_RestrictedCash"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_MexmarOffshoreInternationalMember" xlink:label="smhi_MexmarOffshoreInternationalMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RelatedPartyTransactionAmountsOfTransaction" xlink:label="us-gaap_RelatedPartyTransactionAmountsOfTransaction"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_OffshoreVesselHoldingsMember" xlink:label="smhi_OffshoreVesselHoldingsMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_PercentageOfInitialLimitedPartnerInterestsAndGeneralPartnerInterestsAndInitialLpInterestsHeldByUnrelatedThirdParties" xlink:label="smhi_PercentageOfInitialLimitedPartnerInterestsAndGeneralPartnerInterestsAndInitialLpInterestsHeldByUnrelatedThirdParties"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_Investments" xlink:label="us-gaap_Investments"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EquityMethodInvestmentOwnershipPercentage" xlink:label="us-gaap_EquityMethodInvestmentOwnershipPercentage"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_EquityMethodInvestmentOwnershipAmount" xlink:label="smhi_EquityMethodInvestmentOwnershipAmount"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_MinorityInterestInPreferredUnitHolders" xlink:label="us-gaap_MinorityInterestInPreferredUnitHolders"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_MinorityInterestOwnershipPercentageByParent" xlink:label="us-gaap_MinorityInterestOwnershipPercentageByParent"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ProceedsFromSaleOfInterestInPartnershipUnit" xlink:label="us-gaap_ProceedsFromSaleOfInterestInPartnershipUnit"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ProceedsFromIssuanceOfDebt" xlink:label="us-gaap_ProceedsFromIssuanceOfDebt"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ProceedsFromIssuanceOfRedeemablePreferredStock" xlink:label="us-gaap_ProceedsFromIssuanceOfRedeemablePreferredStock"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LimitedPartnersCapitalAccount" xlink:label="us-gaap_LimitedPartnersCapitalAccount"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners" xlink:label="us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_VesselManagementFees" xlink:label="smhi_VesselManagementFees"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_LoanAcquired" xlink:label="smhi_LoanAcquired"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued" xlink:label="us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_BusinessCombinationAssumedAndGuaranteeAmount" xlink:label="smhi_BusinessCombinationAssumedAndGuaranteeAmount"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentRedemptionDescription" xlink:label="us-gaap_DebtInstrumentRedemptionDescription"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_NotesRedeemableDenominationAmount" xlink:label="smhi_NotesRedeemableDenominationAmount"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentRedemptionPricePercentage" xlink:label="us-gaap_DebtInstrumentRedemptionPricePercentage"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_ConvertibleNotesOutstanding" xlink:label="smhi_ConvertibleNotesOutstanding"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_DebtInstrumentConversionPricePercentage" xlink:label="smhi_DebtInstrumentConversionPricePercentage"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_DebtInstrumentPercentageOfNewConvertibleNoteToBePurchased" xlink:label="smhi_DebtInstrumentPercentageOfNewConvertibleNoteToBePurchased"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_DebtInstrumentPercentageOfNewConvertibleNoteToBeRedeemed" xlink:label="smhi_DebtInstrumentPercentageOfNewConvertibleNoteToBeRedeemed"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ProceedsFromSaleOfEquityMethodInvestments" xlink:label="us-gaap_ProceedsFromSaleOfEquityMethodInvestments"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentPeriodicPaymentPrincipal" xlink:label="us-gaap_DebtInstrumentPeriodicPaymentPrincipal"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentFrequencyOfPeriodicPayment" xlink:label="us-gaap_DebtInstrumentFrequencyOfPeriodicPayment"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_DebtInstrumentQuarterlyPrincipalPayments" xlink:label="smhi_DebtInstrumentQuarterlyPrincipalPayments"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_PercentageOfInterestAccruesUnderCreditFacilityPlusMandatoryCost" xlink:label="smhi_PercentageOfInterestAccruesUnderCreditFacilityPlusMandatoryCost"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentMaturityDate" xlink:label="us-gaap_DebtInstrumentMaturityDate"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PaymentsOfDebtExtinguishmentCosts" xlink:label="us-gaap_PaymentsOfDebtExtinguishmentCosts"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_NumberOfVesselsOwned" xlink:label="smhi_NumberOfVesselsOwned"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired" xlink:label="us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_AverageAgeOfVessels" xlink:label="smhi_AverageAgeOfVessels"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_OwnershipPercentage" xlink:label="smhi_OwnershipPercentage"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_BusinessCombinationConsiderationTransferred1" xlink:label="us-gaap_BusinessCombinationConsiderationTransferred1"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_PercentageSaleOfEquity" xlink:label="smhi_PercentageSaleOfEquity"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ConvertibleDebt" xlink:label="us-gaap_ConvertibleDebt"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentInterestRateTerms" xlink:label="us-gaap_DebtInstrumentInterestRateTerms"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_PercentageOfConvertibleNotesConvertedIntoCommonStock" xlink:label="smhi_PercentageOfConvertibleNotesConvertedIntoCommonStock"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentConvertibleTermsOfConversionFeature" xlink:label="us-gaap_DebtInstrumentConvertibleTermsOfConversionFeature"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtConversionOriginalDebtAmount1" xlink:label="us-gaap_DebtConversionOriginalDebtAmount1"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1" xlink:label="us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentConvertibleConversionRatio1" xlink:label="us-gaap_DebtInstrumentConvertibleConversionRatio1"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentFaceAmount" xlink:label="us-gaap_DebtInstrumentFaceAmount"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentConvertibleConversionPrice1" xlink:label="us-gaap_DebtInstrumentConvertibleConversionPrice1"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtConversionConvertedInstrumentSharesIssued1" xlink:label="us-gaap_DebtConversionConvertedInstrumentSharesIssued1"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage" xlink:label="us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DebtInstrumentInterestRateEffectivePercentage" xlink:label="us-gaap_DebtInstrumentInterestRateEffectivePercentage"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:label="us-gaap_StockIssuedDuringPeriodSharesNewIssues"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfWarrantOrRightOutstanding" xlink:label="us-gaap_ClassOfWarrantOrRightOutstanding"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights" xlink:label="us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockIssuedDuringPeriodValueNewIssues" xlink:label="us-gaap_StockIssuedDuringPeriodValueNewIssues"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_ClassOfWarrantOrRightExercisedDuringPeriod" xlink:label="smhi_ClassOfWarrantOrRightExercisedDuringPeriod"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_DebtIndebtedness" xlink:label="smhi_DebtIndebtedness"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PartnersCapitalAccountContributions" xlink:label="us-gaap_PartnersCapitalAccountContributions"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EquityMethodInvestmentAggregateCost" xlink:label="us-gaap_EquityMethodInvestmentAggregateCost"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LongTermDebt" xlink:label="us-gaap_LongTermDebt"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LongTermPurchaseCommitmentAmount" xlink:label="us-gaap_LongTermPurchaseCommitmentAmount"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_NotesPayableRelatedPartiesCurrentAndNoncurrent" xlink:label="us-gaap_NotesPayableRelatedPartiesCurrentAndNoncurrent"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_TotalPurchasePrice" xlink:label="smhi_TotalPurchasePrice"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_GainLossOnEquityEarnings" xlink:label="smhi_GainLossOnEquityEarnings"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_DistributionReceived" xlink:label="smhi_DistributionReceived"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_ExcessOfDistributionReceived" xlink:label="smhi_ExcessOfDistributionReceived"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_BusinessCombinationConsiderationTransferredPercentage" xlink:label="smhi_BusinessCombinationConsiderationTransferredPercentage"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_LoanInExchange" xlink:label="smhi_LoanInExchange"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_LoanEarlyRepayment" xlink:label="smhi_LoanEarlyRepayment"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_InterestPayableCurrentAndNoncurrent" xlink:label="us-gaap_InterestPayableCurrentAndNoncurrent"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_FinancingAgreement" xlink:label="smhi_FinancingAgreement"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RevenueFromContractWithCustomerIncludingAssessedTax" xlink:label="us-gaap_RevenueFromContractWithCustomerIncludingAssessedTax"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_BusinessAcquisitionAxis" xlink:to="us-gaap_BusinessAcquisitionAcquireeDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SaleOfStockNameOfTransactionDomain" xlink:to="us-gaap_PrivatePlacementMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_BusinessAcquisitionAcquireeDomain" xlink:to="smhi_ExchangeMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_EquityMethodInvesteeNameDomain" xlink:to="smhi_OSVPartnersMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_TypeOfArrangementAxis" xlink:to="us-gaap_ArrangementsAndNonarrangementTransactionsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentRedemptionPeriodDomain" xlink:to="us-gaap_DebtInstrumentRedemptionPeriodOneMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_RangeAxis" xlink:to="srt_RangeMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:to="us-gaap_RelatedPartyDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:to="us-gaap_RelatedPartyDomain_default" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_RepurchaseAgreementCounterpartyNameDomain" xlink:to="smhi_CarolineMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_SegmentGeographicalDomain" xlink:to="country_BR" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_RangeMember" xlink:to="srt_MaximumMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_SubsidiarySaleOfStockAxis" xlink:to="us-gaap_SaleOfStockNameOfTransactionDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="smhi_PreferredInterestsAndClassAPreferredInterestsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="dei_LegalEntityAxis" xlink:to="dei_EntityDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_LongtermDebtTypeAxis" xlink:to="us-gaap_LongtermDebtTypeDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_CreditFacilityDomain" xlink:to="smhi_OSVCreditFacilityMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_CreditFacilityAxis" xlink:to="us-gaap_CreditFacilityDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyDomain" xlink:to="smhi_SEACORHoldingsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfWarrantOrRightDomain" xlink:to="smhi_WarrantsIssuedInPrivatePlacementMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_DebtConversionByUniqueDescriptionAxis" xlink:to="us-gaap_DebtConversionNameDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_RelatedPartyTransactionAxis" xlink:to="us-gaap_RelatedPartyTransactionDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_RelatedPartyTransactionAxis" xlink:to="us-gaap_RelatedPartyTransactionDomain_default" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_PartnerTypeOfPartnersCapitalAccountAxis" xlink:to="us-gaap_PartnerTypeOfPartnersCapitalAccountNameDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xlink:to="srt_EquityMethodInvesteeNameDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:to="smhi_TaxRefundAgreementMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementClassOfStockAxis" xlink:to="us-gaap_ClassOfStockDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementClassOfStockAxis" xlink:to="us-gaap_ClassOfStockDomain_default" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityInterestIssuedOrIssuableTypeDomain" xlink:to="us-gaap_CommonStockMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_OwnershipDomain" xlink:to="smhi_SubsidiariesOfCMEMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_StatementGeographicalAxis" xlink:to="srt_SegmentGeographicalDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_EquityInterestIssuedOrIssuableByTypeAxis" xlink:to="us-gaap_EquityInterestIssuedOrIssuableTypeDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_DebtInstrumentAxis" xlink:to="us-gaap_DebtInstrumentNameDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_CounterpartyNameAxis" xlink:to="srt_RepurchaseAgreementCounterpartyNameDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionDomain" xlink:to="smhi_TransitionServicesAgreementMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_DebtInstrumentRedemptionPeriodAxis" xlink:to="us-gaap_DebtInstrumentRedemptionPeriodDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityMethodInvestmentNonconsolidatedInvesteeDomain" xlink:to="smhi_OPEMMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="smhi_SeniorPIKToggleNotesDueTwoThousandTwentySixMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_ClassOfWarrantOrRightAxis" xlink:to="us-gaap_ClassOfWarrantOrRightDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:to="us-gaap_PropertyPlantAndEquipmentTypeDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="smhi_RelatedPartyTransactionsMinimumAmountOfTransactionsForReviewAndApproval" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_EntityDomain" xlink:to="smhi_SeabulkOverseasMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PartnerTypeOfPartnersCapitalAccountNameDomain" xlink:to="us-gaap_LimitedPartnerMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_OwnershipAxis" xlink:to="srt_OwnershipDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_TitleOfIndividualWithRelationshipToEntityDomain" xlink:to="smhi_NonExecutiveChairmanMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable" xlink:to="us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_TitleOfIndividualAxis" xlink:to="srt_TitleOfIndividualWithRelationshipToEntityDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="smhi_PlatformSupplyVesselsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_EquityMethodInvestmentNonconsolidatedInvesteeAxis" xlink:to="us-gaap_EquityMethodInvestmentNonconsolidatedInvesteeDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtConversionNameDomain" xlink:to="smhi_ConvertibleSeniorNotesConvertedToWarrantsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LongtermDebtTypeDomain" xlink:to="smhi_CashInterestMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_BusinessAcquisitionAcquireeDomain" xlink:to="smhi_ThirdPartyLenderMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_EquityMethodInvesteeNameDomain" xlink:to="smhi_OSVPartnersOneMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentRedemptionPeriodDomain" xlink:to="us-gaap_DebtInstrumentRedemptionPeriodTwoMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_RepurchaseAgreementCounterpartyNameDomain" xlink:to="smhi_CarolineIIMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_RangeMember" xlink:to="srt_MinimumMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_CreditFacilityDomain" xlink:to="smhi_TermLoanMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyDomain" xlink:to="smhi_TwoThousandSeventeenPreferredInterestsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfWarrantOrRightDomain" xlink:to="smhi_OtherThanCarlyleMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:to="smhi_MergerConsiderationMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_OwnershipDomain" xlink:to="smhi_SubsidiaryOfMexMarMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionDomain" xlink:to="smhi_ClassAPreferredInterestsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="smhi_ConvertibleSeniorNotesDueTwoThousandTwentySixMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="us-gaap_GuaranteeObligationsMaximumExposure" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_EntityDomain" xlink:to="smhi_TalosEnergyIncMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_TitleOfIndividualWithRelationshipToEntityDomain" xlink:to="smhi_PresidentChiefExecutiveOfficerAndDirectorMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable" xlink:to="us-gaap_TypeOfArrangementAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LongtermDebtTypeDomain" xlink:to="smhi_HybridInterestMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_BusinessAcquisitionAcquireeDomain" xlink:to="smhi_PrincipalMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_EquityMethodInvesteeNameDomain" xlink:to="smhi_MexMarMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentRedemptionPeriodDomain" xlink:to="us-gaap_DebtInstrumentRedemptionPeriodThreeMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_RepurchaseAgreementCounterpartyNameDomain" xlink:to="smhi_CarlyleGroupMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:to="smhi_PaymentInKindPIKLoanMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_OwnershipDomain" xlink:to="smhi_OTMMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionDomain" xlink:to="smhi_SecondLienDebtMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="smhi_GuaranteedNotesMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="us-gaap_InterestExpenseRelatedParty" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_TitleOfIndividualWithRelationshipToEntityDomain" xlink:to="smhi_ExecutiveVicePresidentAndChiefFinancialOfficerMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable" xlink:to="us-gaap_RelatedPartyTransactionAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LongtermDebtTypeDomain" xlink:to="smhi_HybridInterestPaidInCashMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_BusinessAcquisitionAcquireeDomain" xlink:to="smhi_MergerAgreementMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_EquityMethodInvesteeNameDomain" xlink:to="smhi_MEXMAROffshoreMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:to="smhi_MergerConsiderationAndPaymentInKindLoanConsiderationMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_OwnershipDomain" xlink:to="smhi_OsvPartnerMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="smhi_ConvertibleSeniorNotesMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="us-gaap_ProceedsFromIncomeTaxRefunds" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable" xlink:to="srt_RangeAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LongtermDebtTypeDomain" xlink:to="smhi_HybridInterestPaymentInKindMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_BusinessAcquisitionAcquireeDomain" xlink:to="smhi_WindcatWorkboatsFacilitiesMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_EquityMethodInvesteeNameDomain" xlink:to="smhi_ClassAPreferredInterestsCarolineMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:to="smhi_PriorToClosingOfFrameworkAgreementMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_OwnershipDomain" xlink:to="smhi_OSVPartnerOneMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="smhi_ConvertibleSeniorNotesDueTwoThousandTwentyThreeMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="smhi_PercentageOfNetOperatingLossesFacilitateTaxSavings" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable" xlink:to="srt_TitleOfIndividualAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="5" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_BusinessAcquisitionAcquireeDomain" xlink:to="smhi_UPOffshoresMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="5" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_EquityMethodInvesteeNameDomain" xlink:to="smhi_PIKLoanDebtAndCarolineTwoMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="5" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="smhi_MexMarOriginalFacilityAgreementMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="5" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="smhi_InterestReceived" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="5" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable" xlink:to="srt_OwnershipAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="6" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_EquityMethodInvesteeNameDomain" xlink:to="smhi_ClassAPreferredInterestsCarolineTwoMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="6" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="smhi_MexMarSecondAmendedAndRestatedFacilityAgreementMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="6" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="smhi_TransactionFee" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="6" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable" xlink:to="us-gaap_BusinessAcquisitionAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="7" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_EquityMethodInvesteeNameDomain" xlink:to="smhi_PIKLoanDebtMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="7" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="smhi_MexMarThirdAmendedAndRestatedFacilityAgreementMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="7" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="smhi_CashTaxRefundsWithoutRestrictionsToUse" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="7" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable" xlink:to="us-gaap_CreditFacilityAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="8" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_EquityMethodInvesteeNameDomain" xlink:to="smhi_CMEMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="8" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="smhi_LenderNonRecourseMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="8" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="smhi_CashTaxRefundsWithRestrictionsToUse" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="8" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable" xlink:to="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="9" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_EquityMethodInvesteeNameDomain" xlink:to="smhi_SEACORMarlinLLCMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="9" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="smhi_TaxRefundsRestrictedCash" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="9" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable" xlink:to="us-gaap_PartnerTypeOfPartnersCapitalAccountAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="10" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_EquityMethodInvesteeNameDomain" xlink:to="smhi_OVHMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="10" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="us-gaap_RestrictedCash" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="10" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable" xlink:to="us-gaap_EquityInterestIssuedOrIssuableByTypeAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="11" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_EquityMethodInvesteeNameDomain" xlink:to="smhi_MexmarOffshoreInternationalMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="11" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="us-gaap_RelatedPartyTransactionAmountsOfTransaction" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="11" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable" xlink:to="us-gaap_StatementClassOfStockAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="12" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_EquityMethodInvesteeNameDomain" xlink:to="smhi_OffshoreVesselHoldingsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="12" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="smhi_PercentageOfInitialLimitedPartnerInterestsAndGeneralPartnerInterestsAndInitialLpInterestsHeldByUnrelatedThirdParties" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="12" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable" xlink:to="srt_CounterpartyNameAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="13" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="us-gaap_Investments" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="13" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable" xlink:to="us-gaap_PropertyPlantAndEquipmentByTypeAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="14" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="us-gaap_EquityMethodInvestmentOwnershipPercentage" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="14" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable" xlink:to="dei_LegalEntityAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="15" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="smhi_EquityMethodInvestmentOwnershipAmount" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="15" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable" xlink:to="us-gaap_DebtConversionByUniqueDescriptionAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="16" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="us-gaap_MinorityInterestInPreferredUnitHolders" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="16" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable" xlink:to="us-gaap_DebtInstrumentAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="17" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="us-gaap_MinorityInterestOwnershipPercentageByParent" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="17" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable" xlink:to="us-gaap_ClassOfWarrantOrRightAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="18" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="us-gaap_ProceedsFromSaleOfInterestInPartnershipUnit" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="18" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable" xlink:to="us-gaap_DebtInstrumentRedemptionPeriodAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="19" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="us-gaap_ProceedsFromIssuanceOfDebt" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="19" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable" xlink:to="us-gaap_LongtermDebtTypeAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="20" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="us-gaap_ProceedsFromIssuanceOfRedeemablePreferredStock" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="20" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable" xlink:to="us-gaap_SubsidiarySaleOfStockAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="21" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="us-gaap_LimitedPartnersCapitalAccount" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="21" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable" xlink:to="srt_StatementGeographicalAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="22" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="22" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable" xlink:to="us-gaap_EquityMethodInvestmentNonconsolidatedInvesteeAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="23" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="smhi_VesselManagementFees" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="24" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="smhi_LoanAcquired" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="25" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="26" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="smhi_BusinessCombinationAssumedAndGuaranteeAmount" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="27" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="us-gaap_DebtInstrumentRedemptionDescription" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="28" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="smhi_NotesRedeemableDenominationAmount" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="29" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="us-gaap_DebtInstrumentRedemptionPricePercentage" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="30" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="smhi_ConvertibleNotesOutstanding" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="31" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="smhi_DebtInstrumentConversionPricePercentage" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="32" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="smhi_DebtInstrumentPercentageOfNewConvertibleNoteToBePurchased" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="33" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="smhi_DebtInstrumentPercentageOfNewConvertibleNoteToBeRedeemed" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="34" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="us-gaap_ProceedsFromSaleOfEquityMethodInvestments" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="35" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="us-gaap_DebtInstrumentPeriodicPaymentPrincipal" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="36" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="us-gaap_DebtInstrumentFrequencyOfPeriodicPayment" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="37" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="smhi_DebtInstrumentQuarterlyPrincipalPayments" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="38" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="smhi_PercentageOfInterestAccruesUnderCreditFacilityPlusMandatoryCost" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="39" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="us-gaap_DebtInstrumentMaturityDate" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="40" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="us-gaap_PaymentsOfDebtExtinguishmentCosts" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="41" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="smhi_NumberOfVesselsOwned" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="42" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="43" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="smhi_AverageAgeOfVessels" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="44" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="smhi_OwnershipPercentage" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="45" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="us-gaap_BusinessCombinationConsiderationTransferred1" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="46" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="smhi_PercentageSaleOfEquity" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="47" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="us-gaap_ConvertibleDebt" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="48" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="us-gaap_DebtInstrumentInterestRateTerms" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="49" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="smhi_PercentageOfConvertibleNotesConvertedIntoCommonStock" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="50" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="us-gaap_DebtInstrumentConvertibleTermsOfConversionFeature" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="51" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="us-gaap_DebtConversionOriginalDebtAmount1" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="52" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="53" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="us-gaap_DebtInstrumentConvertibleConversionRatio1" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="54" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="us-gaap_DebtInstrumentFaceAmount" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="55" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="us-gaap_DebtInstrumentConvertibleConversionPrice1" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="56" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="us-gaap_DebtConversionConvertedInstrumentSharesIssued1" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="57" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="us-gaap_DebtInstrumentInterestRateStatedPercentage" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="58" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="us-gaap_DebtInstrumentInterestRateEffectivePercentage" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="59" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="us-gaap_StockIssuedDuringPeriodSharesNewIssues" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="60" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="us-gaap_ClassOfWarrantOrRightOutstanding" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="61" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="62" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="us-gaap_StockIssuedDuringPeriodValueNewIssues" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="63" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="smhi_ClassOfWarrantOrRightExercisedDuringPeriod" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="64" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="smhi_DebtIndebtedness" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="65" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="us-gaap_PartnersCapitalAccountContributions" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="66" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="us-gaap_EquityMethodInvestmentAggregateCost" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="67" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="us-gaap_LongTermDebt" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="68" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="us-gaap_LongTermPurchaseCommitmentAmount" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="69" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="us-gaap_NotesPayableRelatedPartiesCurrentAndNoncurrent" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="70" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="smhi_TotalPurchasePrice" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="71" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="smhi_GainLossOnEquityEarnings" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="72" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="smhi_DistributionReceived" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="73" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="smhi_ExcessOfDistributionReceived" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="74" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="smhi_BusinessCombinationConsiderationTransferredPercentage" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="75" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="smhi_LoanInExchange" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="76" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="smhi_LoanEarlyRepayment" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="77" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="us-gaap_InterestPayableCurrentAndNoncurrent" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="78" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="smhi_FinancingAgreement" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="79" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="us-gaap_RevenueFromContractWithCustomerIncludingAssessedTax" priority="2" use="optional"/>
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureCommitmentsAndContingenciesAdditionalInformationDetails">
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_CommitmentsAndContingenciesLineItems" xlink:label="smhi_CommitmentsAndContingenciesLineItems"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_CommitmentsAndContingenciesTable" xlink:label="smhi_CommitmentsAndContingenciesTable"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_LitigationCaseTypeDomain" xlink:label="srt_LitigationCaseTypeDomain"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_DeficiencyNoticeMember" xlink:label="smhi_DeficiencyNoticeMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeAxis" xlink:label="srt_RangeAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RangeMember" xlink:label="srt_RangeMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_RepurchaseAgreementCounterpartyNameDomain" xlink:label="srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_SeabulkOverseasMember" xlink:label="smhi_SeabulkOverseasMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceSheetAmount" xlink:label="us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceSheetAmount"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_MinimumMember" xlink:label="srt_MinimumMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:label="us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_CounterpartyNameAxis" xlink:label="srt_CounterpartyNameAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_LitigationCaseAxis" xlink:label="srt_LitigationCaseAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_LitigationCaseTypeDomain" xlink:label="srt_LitigationCaseTypeDomain_default"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_FSVOffshoreSupportVesselsMember" xlink:label="smhi_FSVOffshoreSupportVesselsMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFourthAnniversary" xlink:label="us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFourthAnniversary"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_MaximumMember" xlink:label="srt_MaximumMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_UnrecordedUnconditionalPurchaseObligationMaximumQuantity" xlink:label="us-gaap_UnrecordedUnconditionalPurchaseObligationMaximumQuantity"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_CostAllocationPercentage" xlink:label="smhi_CostAllocationPercentage"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LossContingencyEstimateOfPossibleLoss" xlink:label="us-gaap_LossContingencyEstimateOfPossibleLoss"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_GuaranteeObligationsMaximumExposure" xlink:label="us-gaap_GuaranteeObligationsMaximumExposure"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="smhi_CommitmentsAndContingenciesLineItems" xlink:to="smhi_CommitmentsAndContingenciesTable" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_LitigationCaseTypeDomain" xlink:to="smhi_DeficiencyNoticeMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_RangeAxis" xlink:to="srt_RangeMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_RepurchaseAgreementCounterpartyNameDomain" xlink:to="smhi_SeabulkOverseasMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_CommitmentsAndContingenciesLineItems" xlink:to="us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceSheetAmount" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_RangeMember" xlink:to="srt_MinimumMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="smhi_CommitmentsAndContingenciesTable" xlink:to="us-gaap_PropertyPlantAndEquipmentByTypeAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_CounterpartyNameAxis" xlink:to="srt_RepurchaseAgreementCounterpartyNameDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_LitigationCaseAxis" xlink:to="srt_LitigationCaseTypeDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="srt_LitigationCaseAxis" xlink:to="srt_LitigationCaseTypeDomain_default" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:to="us-gaap_PropertyPlantAndEquipmentTypeDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="smhi_FSVOffshoreSupportVesselsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_CommitmentsAndContingenciesLineItems" xlink:to="us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFourthAnniversary" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_RangeMember" xlink:to="srt_MaximumMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="smhi_CommitmentsAndContingenciesTable" xlink:to="srt_RangeAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_CommitmentsAndContingenciesLineItems" xlink:to="us-gaap_UnrecordedUnconditionalPurchaseObligationMaximumQuantity" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="smhi_CommitmentsAndContingenciesTable" xlink:to="srt_LitigationCaseAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_CommitmentsAndContingenciesLineItems" xlink:to="smhi_CostAllocationPercentage" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="smhi_CommitmentsAndContingenciesTable" xlink:to="srt_CounterpartyNameAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_CommitmentsAndContingenciesLineItems" xlink:to="us-gaap_LossContingencyEstimateOfPossibleLoss" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="5" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_CommitmentsAndContingenciesLineItems" xlink:to="us-gaap_GuaranteeObligationsMaximumExposure" priority="2" use="optional"/>
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureMajorCustomersAndSegmentInformationAdditionalInformationDetails">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SegmentReportingInformationLineItems" xlink:label="us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:label="us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ConcentrationRiskByTypeAxis" xlink:label="us-gaap_ConcentrationRiskByTypeAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ConcentrationRiskTypeDomain" xlink:label="us-gaap_ConcentrationRiskTypeDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ConcentrationRiskTypeDomain" xlink:label="us-gaap_ConcentrationRiskTypeDomain_default"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_EquityMethodInvesteeNameDomain" xlink:label="srt_EquityMethodInvesteeNameDomain"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_SeacorMarineArabiaMember" xlink:label="smhi_SeacorMarineArabiaMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_SegmentGeographicalDomain" xlink:label="srt_SegmentGeographicalDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_NonUsMember" xlink:label="us-gaap_NonUsMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ConcentrationRiskBenchmarkDomain" xlink:label="us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SalesRevenueNetMember" xlink:label="us-gaap_SalesRevenueNetMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xlink:label="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_StatementGeographicalAxis" xlink:label="srt_StatementGeographicalAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_EquityMethodInvestmentOwnershipPercentage" xlink:label="us-gaap_EquityMethodInvestmentOwnershipPercentage"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_MajorCustomersAxis" xlink:label="srt_MajorCustomersAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_NameOfMajorCustomerDomain" xlink:label="srt_NameOfMajorCustomerDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_NameOfMajorCustomerDomain" xlink:label="srt_NameOfMajorCustomerDomain_default"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_SeacorMarineArabiaLLCMember" xlink:label="smhi_SeacorMarineArabiaLLCMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis" xlink:label="us-gaap_ConcentrationRiskByBenchmarkAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ConcentrationRiskBenchmarkDomain" xlink:label="us-gaap_ConcentrationRiskBenchmarkDomain_default"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CustomerConcentrationRiskMember" xlink:label="us-gaap_CustomerConcentrationRiskMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_StockholdersEquityTotalMember" xlink:label="us-gaap_StockholdersEquityTotalMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RevenueFromContractWithCustomerIncludingAssessedTax" xlink:label="us-gaap_RevenueFromContractWithCustomerIncludingAssessedTax"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_ZamilOffshoreMember" xlink:label="smhi_ZamilOffshoreMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_GeographicConcentrationRiskMember" xlink:label="us-gaap_GeographicConcentrationRiskMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ConcentrationRiskPercentage1" xlink:label="us-gaap_ConcentrationRiskPercentage1"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_TenLargestCustomersMember" xlink:label="smhi_TenLargestCustomersMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_NumberOfCustomer" xlink:label="smhi_NumberOfCustomer"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_ExxonMobilMember" xlink:label="smhi_ExxonMobilMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncomeLossFromEquityMethodInvestments" xlink:label="us-gaap_IncomeLossFromEquityMethodInvestments"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_SaudiAramcoMember" xlink:label="smhi_SaudiAramcoMember"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_SegmentReportingInformationLineItems" xlink:to="us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_ConcentrationRiskByTypeAxis" xlink:to="us-gaap_ConcentrationRiskTypeDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_ConcentrationRiskByTypeAxis" xlink:to="us-gaap_ConcentrationRiskTypeDomain_default" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_EquityMethodInvesteeNameDomain" xlink:to="smhi_SeacorMarineArabiaMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_SegmentGeographicalDomain" xlink:to="us-gaap_NonUsMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ConcentrationRiskBenchmarkDomain" xlink:to="us-gaap_SalesRevenueNetMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xlink:to="srt_EquityMethodInvesteeNameDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:to="us-gaap_ConcentrationRiskByTypeAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_StatementGeographicalAxis" xlink:to="srt_SegmentGeographicalDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentReportingInformationLineItems" xlink:to="us-gaap_EquityMethodInvestmentOwnershipPercentage" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_MajorCustomersAxis" xlink:to="srt_NameOfMajorCustomerDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="srt_MajorCustomersAxis" xlink:to="srt_NameOfMajorCustomerDomain_default" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_NameOfMajorCustomerDomain" xlink:to="smhi_SeacorMarineArabiaLLCMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_ConcentrationRiskByBenchmarkAxis" xlink:to="us-gaap_ConcentrationRiskBenchmarkDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_ConcentrationRiskByBenchmarkAxis" xlink:to="us-gaap_ConcentrationRiskBenchmarkDomain_default" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ConcentrationRiskTypeDomain" xlink:to="us-gaap_CustomerConcentrationRiskMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ConcentrationRiskBenchmarkDomain" xlink:to="us-gaap_StockholdersEquityTotalMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:to="us-gaap_ConcentrationRiskByBenchmarkAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentReportingInformationLineItems" xlink:to="us-gaap_RevenueFromContractWithCustomerIncludingAssessedTax" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_NameOfMajorCustomerDomain" xlink:to="smhi_ZamilOffshoreMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ConcentrationRiskTypeDomain" xlink:to="us-gaap_GeographicConcentrationRiskMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:to="srt_MajorCustomersAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentReportingInformationLineItems" xlink:to="us-gaap_ConcentrationRiskPercentage1" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_NameOfMajorCustomerDomain" xlink:to="smhi_TenLargestCustomersMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:to="srt_StatementGeographicalAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentReportingInformationLineItems" xlink:to="smhi_NumberOfCustomer" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_NameOfMajorCustomerDomain" xlink:to="smhi_ExxonMobilMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:to="srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentReportingInformationLineItems" xlink:to="us-gaap_IncomeLossFromEquityMethodInvestments" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_NameOfMajorCustomerDomain" xlink:to="smhi_SaudiAramcoMember" priority="2" use="optional"/>
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureMajorCustomersAndSegmentInformationScheduleOfSegmentReportingInformationBySegmentDetails">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SegmentReportingInformationLineItems" xlink:label="us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:label="us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ProductOrServiceAxis" xlink:label="srt_ProductOrServiceAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain_default"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_SegmentGeographicalDomain" xlink:label="srt_SegmentGeographicalDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/country/2022/country-2022.xsd#country_US" xlink:label="country_US"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_StatementGeographicalAxis" xlink:label="srt_StatementGeographicalAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_RevenueFromContractWithCustomerIncludingAssessedTax" xlink:label="us-gaap_RevenueFromContractWithCustomerIncludingAssessedTax"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_TimeCharterMember" xlink:label="smhi_TimeCharterMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_AfricaAndEuropeMember" xlink:label="smhi_AfricaAndEuropeMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_CostOfGoodsAndServicesSoldAndAdjustment" xlink:label="smhi_CostOfGoodsAndServicesSoldAndAdjustment"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_BareboatCharterMember" xlink:label="smhi_BareboatCharterMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_MiddleEastAndAsiaMember" xlink:label="smhi_MiddleEastAndAsiaMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_GrossProfit" xlink:label="us-gaap_GrossProfit"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_OtherMarineServicesMember" xlink:label="smhi_OtherMarineServicesMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_LatinAmericaMember" xlink:label="srt_LatinAmericaMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_LeaseExpense" xlink:label="smhi_LeaseExpense"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_PersonnelMember" xlink:label="smhi_PersonnelMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_GeneralAndAdministrativeExpenseIncludingShortTermLeaseExpense" xlink:label="smhi_GeneralAndAdministrativeExpenseIncludingShortTermLeaseExpense"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_RepairsAndMaintenanceMember" xlink:label="smhi_RepairsAndMaintenanceMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DepreciationDepletionAndAmortization" xlink:label="us-gaap_DepreciationDepletionAndAmortization"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_DrydockingMember" xlink:label="smhi_DrydockingMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OtherCostAndExpenseOperating" xlink:label="us-gaap_OtherCostAndExpenseOperating"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_InsuranceAndLossReservesMember" xlink:label="smhi_InsuranceAndLossReservesMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_GainLossOnSalesOfAssetsAndAssetImpairmentCharges" xlink:label="us-gaap_GainLossOnSalesOfAssetsAndAssetImpairmentCharges"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_FuelLubesAndSuppliesMember" xlink:label="smhi_FuelLubesAndSuppliesMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OperatingIncomeLoss" xlink:label="us-gaap_OperatingIncomeLoss"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_OtherDirectCostsAndExpensesMember" xlink:label="smhi_OtherDirectCostsAndExpensesMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_PropertyPlantAndEquipmentGross" xlink:label="us-gaap_PropertyPlantAndEquipmentGross"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" xlink:label="us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_PropertyPlantAndEquipmentExcludingConstructionInProgress" xlink:label="smhi_PropertyPlantAndEquipmentExcludingConstructionInProgress"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_AssetsExcludingCorporateAssets" xlink:label="smhi_AssetsExcludingCorporateAssets"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_SegmentReportingInformationLineItems" xlink:to="us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain_default" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_SegmentGeographicalDomain" xlink:to="country_US" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:to="srt_StatementGeographicalAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_StatementGeographicalAxis" xlink:to="srt_SegmentGeographicalDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentReportingInformationLineItems" xlink:to="us-gaap_RevenueFromContractWithCustomerIncludingAssessedTax" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_ProductsAndServicesDomain" xlink:to="smhi_TimeCharterMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_SegmentGeographicalDomain" xlink:to="smhi_AfricaAndEuropeMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:to="srt_ProductOrServiceAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentReportingInformationLineItems" xlink:to="smhi_CostOfGoodsAndServicesSoldAndAdjustment" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_ProductsAndServicesDomain" xlink:to="smhi_BareboatCharterMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_SegmentGeographicalDomain" xlink:to="smhi_MiddleEastAndAsiaMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentReportingInformationLineItems" xlink:to="us-gaap_GrossProfit" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_ProductsAndServicesDomain" xlink:to="smhi_OtherMarineServicesMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_SegmentGeographicalDomain" xlink:to="srt_LatinAmericaMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentReportingInformationLineItems" xlink:to="smhi_LeaseExpense" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_ProductsAndServicesDomain" xlink:to="smhi_PersonnelMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentReportingInformationLineItems" xlink:to="smhi_GeneralAndAdministrativeExpenseIncludingShortTermLeaseExpense" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_ProductsAndServicesDomain" xlink:to="smhi_RepairsAndMaintenanceMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="5" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentReportingInformationLineItems" xlink:to="us-gaap_DepreciationDepletionAndAmortization" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="5" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_ProductsAndServicesDomain" xlink:to="smhi_DrydockingMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="6" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentReportingInformationLineItems" xlink:to="us-gaap_OtherCostAndExpenseOperating" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="6" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_ProductsAndServicesDomain" xlink:to="smhi_InsuranceAndLossReservesMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="7" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentReportingInformationLineItems" xlink:to="us-gaap_GainLossOnSalesOfAssetsAndAssetImpairmentCharges" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="7" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_ProductsAndServicesDomain" xlink:to="smhi_FuelLubesAndSuppliesMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="8" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentReportingInformationLineItems" xlink:to="us-gaap_OperatingIncomeLoss" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="8" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_ProductsAndServicesDomain" xlink:to="smhi_OtherDirectCostsAndExpensesMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="9" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentReportingInformationLineItems" xlink:to="us-gaap_PropertyPlantAndEquipmentGross" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="10" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentReportingInformationLineItems" xlink:to="us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="11" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentReportingInformationLineItems" xlink:to="smhi_PropertyPlantAndEquipmentExcludingConstructionInProgress" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="12" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentReportingInformationLineItems" xlink:to="smhi_AssetsExcludingCorporateAssets" priority="2" use="optional"/>
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureMajorCustomersAndSegmentInformationScheduleOfSegmentReportingInformationBySegmentParentheticalDetails">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_SegmentReportingInformationLineItems" xlink:label="us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:label="us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ConsolidationItemsAxis" xlink:label="srt_ConsolidationItemsAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ConsolidationItemsDomain" xlink:label="srt_ConsolidationItemsDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ConsolidationItemsDomain" xlink:label="srt_ConsolidationItemsDomain_default"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_Assets" xlink:label="us-gaap_Assets"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_CorporateNonSegmentMember" xlink:label="us-gaap_CorporateNonSegmentMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperation" xlink:label="us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperation"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_SegmentReportingInformationLineItems" xlink:to="us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_ConsolidationItemsAxis" xlink:to="srt_ConsolidationItemsDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="srt_ConsolidationItemsAxis" xlink:to="srt_ConsolidationItemsDomain_default" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:to="srt_ConsolidationItemsAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentReportingInformationLineItems" xlink:to="us-gaap_Assets" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_ConsolidationItemsDomain" xlink:to="us-gaap_CorporateNonSegmentMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SegmentReportingInformationLineItems" xlink:to="us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperation" priority="2" use="optional"/>
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureDiscontinuedOperationsAdditionalInformationDetails">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems" xlink:label="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable" xlink:label="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis" xlink:label="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain" xlink:label="us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain" xlink:label="us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_default"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DisposalGroupClassificationDomain" xlink:label="us-gaap_DisposalGroupClassificationDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DiscontinuedOperationsHeldforsaleMember" xlink:label="us-gaap_DiscontinuedOperationsHeldforsaleMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DisposalGroupClassificationAxis" xlink:label="us-gaap_DisposalGroupClassificationAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DisposalGroupClassificationDomain" xlink:label="us-gaap_DisposalGroupClassificationDomain_default"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_WindcatWorkboatsLtdMember" xlink:label="smhi_WindcatWorkboatsLtdMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DiscontinuedOperationGainLossOnDisposalOfDiscontinuedOperationNetOfTax" xlink:label="us-gaap_DiscontinuedOperationGainLossOnDisposalOfDiscontinuedOperationNetOfTax"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DiscontinuedOperationGainLossOnDisposalStatementOfIncomeOrComprehensiveIncomeExtensibleEnumeration" xlink:label="us-gaap_DiscontinuedOperationGainLossOnDisposalStatementOfIncomeOrComprehensiveIncomeExtensibleEnumeration"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems" xlink:to="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis" xlink:to="us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis" xlink:to="us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_default" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DisposalGroupClassificationDomain" xlink:to="us-gaap_DiscontinuedOperationsHeldforsaleMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_DisposalGroupClassificationAxis" xlink:to="us-gaap_DisposalGroupClassificationDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_DisposalGroupClassificationAxis" xlink:to="us-gaap_DisposalGroupClassificationDomain_default" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable" xlink:to="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain" xlink:to="smhi_WindcatWorkboatsLtdMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems" xlink:to="us-gaap_DiscontinuedOperationGainLossOnDisposalOfDiscontinuedOperationNetOfTax" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable" xlink:to="us-gaap_DisposalGroupClassificationAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems" xlink:to="us-gaap_DiscontinuedOperationGainLossOnDisposalStatementOfIncomeOrComprehensiveIncomeExtensibleEnumeration" priority="2" use="optional"/>
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.seacormarine.com/20221231/taxonomy/role/Role_DisclosureDiscontinuedOperationsScheduleOfAssetsHeldForSaleDetails">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems" xlink:label="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable" xlink:label="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis" xlink:label="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain" xlink:label="us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ProductOrServiceAxis" xlink:label="srt_ProductOrServiceAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd#srt_ProductsAndServicesDomain" xlink:label="srt_ProductsAndServicesDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DisposalGroupClassificationDomain" xlink:label="us-gaap_DisposalGroupClassificationDomain"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DiscontinuedOperationsHeldforsaleMember" xlink:label="us-gaap_DiscontinuedOperationsHeldforsaleMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_DisposalGroupDiscontinuedOperationCostsAndExpensesAbstract" xlink:label="smhi_DisposalGroupDiscontinuedOperationCostsAndExpensesAbstract"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationOperatingExpense" xlink:label="us-gaap_DisposalGroupIncludingDiscontinuedOperationOperatingExpense"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DisposalGroupClassificationAxis" xlink:label="us-gaap_DisposalGroupClassificationAxis"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationAbstract" xlink:label="us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationAbstract"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrent" xlink:label="us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrent"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationAbstract" xlink:label="us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationAbstract"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrent" xlink:label="us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrent"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_TimeCharterMember" xlink:label="smhi_TimeCharterMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_DisposalGroupDiscontinuedOperationOperatingRevenueAbstract" xlink:label="smhi_DisposalGroupDiscontinuedOperationOperatingRevenueAbstract"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationRevenue" xlink:label="us-gaap_DisposalGroupIncludingDiscontinuedOperationRevenue"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_WindcatWorkboatsLtdMember" xlink:label="smhi_WindcatWorkboatsLtdMember"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_DisposalGroupIncludingDiscontinuedOperationOtherNonoperatingIncomeExpenseAbstract" xlink:label="smhi_DisposalGroupIncludingDiscontinuedOperationOtherNonoperatingIncomeExpenseAbstract"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationInterestIncome" xlink:label="us-gaap_DisposalGroupIncludingDiscontinuedOperationInterestIncome"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationGrossProfitLoss" xlink:label="us-gaap_DisposalGroupIncludingDiscontinuedOperationGrossProfitLoss"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationPropertyPlantAndEquipmentNoncurrent" xlink:label="us-gaap_DisposalGroupIncludingDiscontinuedOperationPropertyPlantAndEquipmentNoncurrent"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationNoncurrent" xlink:label="us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationNoncurrent"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_OtherRevenueMember" xlink:label="smhi_OtherRevenueMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationInterestExpense" xlink:label="us-gaap_DisposalGroupIncludingDiscontinuedOperationInterestExpense"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationGeneralAndAdministrativeExpense" xlink:label="us-gaap_DisposalGroupIncludingDiscontinuedOperationGeneralAndAdministrativeExpense"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationAssetsNoncurrent" xlink:label="us-gaap_DisposalGroupIncludingDiscontinuedOperationAssetsNoncurrent"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation" xlink:label="us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationForeignCurrencyTranslationGainsLosses" xlink:label="us-gaap_DisposalGroupIncludingDiscontinuedOperationForeignCurrencyTranslationGainsLosses"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_DisposalGroupIncludingDiscontinuedOperationLeaseExpense" xlink:label="smhi_DisposalGroupIncludingDiscontinuedOperationLeaseExpense"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperation" xlink:label="us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperation"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_DisposalGroupIncludingDiscontinuedOperationOtherNet" xlink:label="smhi_DisposalGroupIncludingDiscontinuedOperationOtherNet"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationDepreciationAndAmortization" xlink:label="us-gaap_DisposalGroupIncludingDiscontinuedOperationDepreciationAndAmortization"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_DisposalGroupIncludingDiscontinuedOperationOtherNonoperatingIncomeExpense" xlink:label="smhi_DisposalGroupIncludingDiscontinuedOperationOtherNonoperatingIncomeExpense"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationOperatingIncomeLoss" xlink:label="us-gaap_DisposalGroupIncludingDiscontinuedOperationOperatingIncomeLoss"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_DisposalGroupIncludingDiscontinuedOperationIncomeLossBeforeIncomeTaxesAndIncomeLossFromEquityMethodInvestments" xlink:label="smhi_DisposalGroupIncludingDiscontinuedOperationIncomeLossBeforeIncomeTaxesAndIncomeLossFromEquityMethodInvestments"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_DisposalGroupIncludingDiscontinuedOperationIncomeTaxExpenseBenefit" xlink:label="smhi_DisposalGroupIncludingDiscontinuedOperationIncomeTaxExpenseBenefit"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_DisposalGroupIncludingDiscontinuedOperationIncomeLossBeforeEquityMethodInvestmentsAfterTax" xlink:label="smhi_DisposalGroupIncludingDiscontinuedOperationIncomeLossBeforeEquityMethodInvestmentsAfterTax"/>
    <link:loc xlink:type="locator" xlink:href="smhi-20221231.xsd#smhi_DisposalGroupIncludingDiscontinuedOperationIncomeLossFromEquityMethodInvestments" xlink:label="smhi_DisposalGroupIncludingDiscontinuedOperationIncomeLossFromEquityMethodInvestments"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DiscontinuedOperationGainLossOnDisposalOfDiscontinuedOperationNetOfTax" xlink:label="us-gaap_DiscontinuedOperationGainLossOnDisposalOfDiscontinuedOperationNetOfTax"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DiscontinuedOperationGainLossOnDisposalStatementOfIncomeOrComprehensiveIncomeExtensibleEnumeration" xlink:label="us-gaap_DiscontinuedOperationGainLossOnDisposalStatementOfIncomeOrComprehensiveIncomeExtensibleEnumeration"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems" xlink:to="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis" xlink:to="us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_ProductOrServiceAxis" xlink:to="srt_ProductsAndServicesDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DisposalGroupClassificationDomain" xlink:to="us-gaap_DiscontinuedOperationsHeldforsaleMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_DisposalGroupDiscontinuedOperationCostsAndExpensesAbstract" xlink:to="us-gaap_DisposalGroupIncludingDiscontinuedOperationOperatingExpense" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_DisposalGroupClassificationAxis" xlink:to="us-gaap_DisposalGroupClassificationDomain" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable" xlink:to="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationAbstract" xlink:to="us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrent" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationAbstract" xlink:to="us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrent" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_ProductsAndServicesDomain" xlink:to="smhi_TimeCharterMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_DisposalGroupDiscontinuedOperationOperatingRevenueAbstract" xlink:to="us-gaap_DisposalGroupIncludingDiscontinuedOperationRevenue" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain" xlink:to="smhi_WindcatWorkboatsLtdMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems" xlink:to="us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationAbstract" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_DisposalGroupIncludingDiscontinuedOperationOtherNonoperatingIncomeExpenseAbstract" xlink:to="us-gaap_DisposalGroupIncludingDiscontinuedOperationInterestIncome" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_DisposalGroupDiscontinuedOperationCostsAndExpensesAbstract" xlink:to="us-gaap_DisposalGroupIncludingDiscontinuedOperationGrossProfitLoss" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable" xlink:to="us-gaap_DisposalGroupClassificationAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationAbstract" xlink:to="us-gaap_DisposalGroupIncludingDiscontinuedOperationPropertyPlantAndEquipmentNoncurrent" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationAbstract" xlink:to="us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationNoncurrent" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_ProductsAndServicesDomain" xlink:to="smhi_OtherRevenueMember" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems" xlink:to="us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationAbstract" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="1" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_DisposalGroupIncludingDiscontinuedOperationOtherNonoperatingIncomeExpenseAbstract" xlink:to="us-gaap_DisposalGroupIncludingDiscontinuedOperationInterestExpense" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_DisposalGroupDiscontinuedOperationCostsAndExpensesAbstract" xlink:to="us-gaap_DisposalGroupIncludingDiscontinuedOperationGeneralAndAdministrativeExpense" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable" xlink:to="srt_ProductOrServiceAxis" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationAbstract" xlink:to="us-gaap_DisposalGroupIncludingDiscontinuedOperationAssetsNoncurrent" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationAbstract" xlink:to="us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems" xlink:to="smhi_DisposalGroupDiscontinuedOperationOperatingRevenueAbstract" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="2" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_DisposalGroupIncludingDiscontinuedOperationOtherNonoperatingIncomeExpenseAbstract" xlink:to="us-gaap_DisposalGroupIncludingDiscontinuedOperationForeignCurrencyTranslationGainsLosses" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_DisposalGroupDiscontinuedOperationCostsAndExpensesAbstract" xlink:to="smhi_DisposalGroupIncludingDiscontinuedOperationLeaseExpense" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationAbstract" xlink:to="us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperation" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems" xlink:to="smhi_DisposalGroupDiscontinuedOperationCostsAndExpensesAbstract" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_DisposalGroupIncludingDiscontinuedOperationOtherNonoperatingIncomeExpenseAbstract" xlink:to="smhi_DisposalGroupIncludingDiscontinuedOperationOtherNet" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_DisposalGroupDiscontinuedOperationCostsAndExpensesAbstract" xlink:to="us-gaap_DisposalGroupIncludingDiscontinuedOperationDepreciationAndAmortization" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems" xlink:to="smhi_DisposalGroupIncludingDiscontinuedOperationOtherNonoperatingIncomeExpenseAbstract" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="4" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_DisposalGroupIncludingDiscontinuedOperationOtherNonoperatingIncomeExpenseAbstract" xlink:to="smhi_DisposalGroupIncludingDiscontinuedOperationOtherNonoperatingIncomeExpense" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="5" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="smhi_DisposalGroupDiscontinuedOperationCostsAndExpensesAbstract" xlink:to="us-gaap_DisposalGroupIncludingDiscontinuedOperationOperatingIncomeLoss" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="5" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems" xlink:to="smhi_DisposalGroupIncludingDiscontinuedOperationIncomeLossBeforeIncomeTaxesAndIncomeLossFromEquityMethodInvestments" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="6" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems" xlink:to="smhi_DisposalGroupIncludingDiscontinuedOperationIncomeTaxExpenseBenefit" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="7" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems" xlink:to="smhi_DisposalGroupIncludingDiscontinuedOperationIncomeLossBeforeEquityMethodInvestmentsAfterTax" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="8" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems" xlink:to="smhi_DisposalGroupIncludingDiscontinuedOperationIncomeLossFromEquityMethodInvestments" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="9" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems" xlink:to="us-gaap_DiscontinuedOperationGainLossOnDisposalOfDiscontinuedOperationNetOfTax" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="10" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems" xlink:to="us-gaap_DiscontinuedOperationGainLossOnDisposalStatementOfIncomeOrComprehensiveIncomeExtensibleEnumeration" priority="2" use="optional"/>
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://fasb.org/us-gaap/role/eedm/ExtensibleEnumerationLists">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncomeStatementAbstract" xlink:label="us-gaap_IncomeStatementAbstract"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax" xlink:label="us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_GainLossOnSalesOfAssetsAndAssetImpairmentCharges" xlink:label="us-gaap_GainLossOnSalesOfAssetsAndAssetImpairmentCharges"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_LiabilitiesAbstract" xlink:label="us-gaap_LiabilitiesAbstract"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_DerivativeLiabilitiesCurrent" xlink:label="us-gaap_DerivativeLiabilitiesCurrent"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_AssetsAbstract" xlink:label="us-gaap_AssetsAbstract"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd#us-gaap_OtherReceivablesNetCurrent" xlink:label="us-gaap_OtherReceivablesNetCurrent"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncomeStatementAbstract" xlink:to="us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="3" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncomeStatementAbstract" xlink:to="us-gaap_GainLossOnSalesOfAssetsAndAssetImpairmentCharges" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LiabilitiesAbstract" xlink:to="us-gaap_DerivativeLiabilitiesCurrent" priority="2" use="optional"/>
    <link:definitionArc xlink:type="arc" order="0" xbrldt:closed="false" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AssetsAbstract" xlink:to="us-gaap_OtherReceivablesNetCurrent" priority="2" use="optional"/>
  </link:definitionLink>
</link:linkbase>
