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<!-- RR Donnelley Xcelerate Taxonomy Schema, based on XBRL 2.1  http://www.rrdonnelley.com/ -->
<!-- Version: 6.21.3 -->
<!-- Round: 5 -->
<!-- Creation date: 2014-11-08T04:24:57Z -->
<!-- Copyright (c) 2005-2013 R.R. Donnelley &amp; Sons Company All Rights Reserved. -->
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  <element name="IncomeTaxesLineItems" id="omex_IncomeTaxesLineItems" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="IncomeTaxesTable" id="omex_IncomeTaxesTable" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrldt:hypercubeItem"/>
  <element name="IndebtednessInterestRatePerYear" id="omex_IndebtednessInterestRatePerYear" type="num:percentItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="IndebtednessInterestRatePerYearUnderDefaultCondition" id="omex_IndebtednessInterestRatePerYearUnderDefaultCondition" type="num:percentItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="InMoneyPotentialCommonSharesMember" id="omex_InMoneyPotentialCommonSharesMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="InterestObligationFromBasisPointVariation" id="omex_InterestObligationFromBasisPointVariation" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="instant" xbrli:balance="credit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="InventoryCurrentAndNonCurrentNet" id="omex_InventoryCurrentAndNonCurrentNet" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="instant" xbrli:balance="debit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="InvestmentForFutureRevenueRights" id="omex_InvestmentForFutureRevenueRights" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="duration" xbrli:balance="debit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="InvestmentInConsolidatedEntity" id="omex_InvestmentInConsolidatedEntity" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="duration" xbrli:balance="debit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="InvestmentMultiplierInCaseOfProjectSuccess" id="omex_InvestmentMultiplierInCaseOfProjectSuccess" type="xbrli:integerItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="InvestmentRepaymentPeriod" id="omex_InvestmentRepaymentPeriod" type="xbrli:durationItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="IssuedWarrantsToAcquireCommonShares" id="omex_IssuedWarrantsToAcquireCommonShares" type="xbrli:sharesItemType" abstract="false" xbrli:periodType="instant" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="LenderMember" id="omex_LenderMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="MarineServiceAccountReceivables" id="omex_MarineServiceAccountReceivables" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="MarineServicesProjectsMember" id="omex_MarineServicesProjectsMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="MarketingFeePercentage" id="omex_MarketingFeePercentage" type="num:percentItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="MaturityPeriodOfConcentrationOfCreditRisk" id="omex_MaturityPeriodOfConcentrationOfCreditRisk" type="xbrli:gYearMonthItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="MaximumIssueOfWarrantsToPurchaseCommonStock" id="omex_MaximumIssueOfWarrantsToPurchaseCommonStock" type="xbrli:sharesItemType" abstract="false" xbrli:periodType="instant" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="MaximumPercentageOfCashFlowEffectOnPresentValueBasis" id="omex_MaximumPercentageOfCashFlowEffectOnPresentValueBasis" type="num:percentItemType" abstract="false" xbrli:periodType="instant" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="MineralExplorationArea" id="omex_MineralExplorationArea" type="xbrli:integerItemType" abstract="false" xbrli:periodType="instant" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="MiningExploratoryServiceRevenue" id="omex_MiningExploratoryServiceRevenue" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="duration" xbrli:balance="credit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="MonacoNotesMember" id="omex_MonacoNotesMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="MonteCarloSimulationsMember" id="omex_MonteCarloSimulationsMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="MortgageAndLoansPayableCurrent" id="omex_MortgageAndLoansPayableCurrent" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="instant" xbrli:balance="credit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="MortgageAndLoansPayableCurrentAndNonCurrent" id="omex_MortgageAndLoansPayableCurrentAndNonCurrent" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="instant" xbrli:balance="credit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="MortgageAndLoansPayableNonCurrent" id="omex_MortgageAndLoansPayableNonCurrent" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="instant" xbrli:balance="credit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="MortgageAndLoansPayableTextBlock" id="omex_MortgageAndLoansPayableTextBlock" type="nonnum:textBlockItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="NeptuneMineralsIncorporatedMember" id="omex_NeptuneMineralsIncorporatedMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="NetIncomeLossAvailableToCommonStockholdersBasicAndDiluted" id="omex_NetIncomeLossAvailableToCommonStockholdersBasicAndDiluted" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="duration" xbrli:balance="credit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="NetOperatingLossCarriedForwardAvailableForOffsettingAgainstFutureTaxableIncomePercentage" id="omex_NetOperatingLossCarriedForwardAvailableForOffsettingAgainstFutureTaxableIncomePercentage" type="num:percentItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="NetOperatingLossCarriedForwardAvailableForOffsettingAgainstFutureTaxableIncomePercentageAsOriginal" id="omex_NetOperatingLossCarriedForwardAvailableForOffsettingAgainstFutureTaxableIncomePercentageAsOriginal" type="num:percentItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="NetOperatingLossCarryBackPeriodOne" id="omex_NetOperatingLossCarryBackPeriodOne" type="xbrli:durationItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="NetOperatingLossCarryBackPeriodOriginal" id="omex_NetOperatingLossCarryBackPeriodOriginal" type="xbrli:durationItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="NinePercentageConvertibleSeniorNotePayableMember" id="omex_NinePercentageConvertibleSeniorNotePayableMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="NoncurrentAssetsExcludingPropertyPlantAndEquipment" id="omex_NoncurrentAssetsExcludingPropertyPlantAndEquipment" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="instant" xbrli:balance="debit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="NumberOfFinancialInstitutionsInWhichCashDeposited" id="omex_NumberOfFinancialInstitutionsInWhichCashDeposited" type="xbrli:integerItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="NumberOfInstitutionalInvestorUnderSecuritiesPurchaseAgreement" id="omex_NumberOfInstitutionalInvestorUnderSecuritiesPurchaseAgreement" type="xbrli:integerItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="NumberOfProjectsAfterBifurcation" id="omex_NumberOfProjectsAfterBifurcation" type="xbrli:integerItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="NumberOfSecuritiesCalledByWarrantsOrRightsUponAdditionalFinancing" id="omex_NumberOfSecuritiesCalledByWarrantsOrRightsUponAdditionalFinancing" type="xbrli:sharesItemType" abstract="false" xbrli:periodType="instant" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="NumberOfStockIncentivePlans" id="omex_NumberOfStockIncentivePlans" type="xbrli:integerItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="NumberOfWhollyOwnedSubsidiaries" id="omex_NumberOfWhollyOwnedSubsidiaries" type="xbrli:integerItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="OceanicaResourcesMember" id="omex_OceanicaResourcesMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="OperatingLossCarryforwardsExpirationYearEndMember" id="omex_OperatingLossCarryforwardsExpirationYearEndMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="OperatingLossCarryforwardsExpirationYearStartMember" id="omex_OperatingLossCarryforwardsExpirationYearStartMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="OperationsAndResearch" id="omex_OperationsAndResearch" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="duration" xbrli:balance="debit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="OtherAccountsReceivableMember" id="omex_OtherAccountsReceivableMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="OutOfMoneyPotentialCommonSharesMember" id="omex_OutOfMoneyPotentialCommonSharesMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="ParticipationRevenueRightsFirstPaymentMember" id="omex_ParticipationRevenueRightsFirstPaymentMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="ParticipationRevenueRightsSecondPaymentMember" id="omex_ParticipationRevenueRightsSecondPaymentMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="ParticipationRevenueRightsThirdPaymentMember" id="omex_ParticipationRevenueRightsThirdPaymentMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="PaymentRestrictedCashHeldAsCollateralOnLoanPayable" id="omex_PaymentRestrictedCashHeldAsCollateralOnLoanPayable" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="duration" xbrli:balance="credit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="PercentageOfAccelerationPaymentOfRemainingFaceValue" id="omex_PercentageOfAccelerationPaymentOfRemainingFaceValue" type="num:percentItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="PercentageOfAdjustedConversionPriceOfQuotedMarketPrices" id="omex_PercentageOfAdjustedConversionPriceOfQuotedMarketPrices" type="num:percentItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="PercentageOfCarryingValueOfAdditionalNoteToDetermineChangeInFairValueOfEmbeddedConversionOption" id="omex_PercentageOfCarryingValueOfAdditionalNoteToDetermineChangeInFairValueOfEmbeddedConversionOption" type="num:percentItemType" abstract="false" xbrli:periodType="instant" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="PercentageOfCashProceedsFromMonetizationOfRecoveredCargo" id="omex_PercentageOfCashProceedsFromMonetizationOfRecoveredCargo" type="num:percentItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="PercentageOfConversionPriceEqualToVolumeWeightedAveragePrice" id="omex_PercentageOfConversionPriceEqualToVolumeWeightedAveragePrice" type="num:percentItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="PercentageOfDebtInstrumentConversionPriceOnMarketPriceOfCommonStock" id="omex_PercentageOfDebtInstrumentConversionPriceOnMarketPriceOfCommonStock" type="num:percentItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="PercentageOfRevenueOwedToCertificateHolders" id="omex_PercentageOfRevenueOwedToCertificateHolders" type="num:percentItemType" abstract="false" xbrli:periodType="instant" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="PercentageOfRevenueOwedToCertificateHoldersPerUnit" id="omex_PercentageOfRevenueOwedToCertificateHoldersPerUnit" type="num:percentItemType" abstract="false" xbrli:periodType="instant" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="PercentageOfSharesPurchasedByAgentInPrivatePlacement" id="omex_PercentageOfSharesPurchasedByAgentInPrivatePlacement" type="num:percentItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="PercentageOfSubsequentCashProceedsAfterReimbursement" id="omex_PercentageOfSubsequentCashProceedsAfterReimbursement" type="num:percentItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="PeriodForAnniversaryOfInitialClosingDate" id="omex_PeriodForAnniversaryOfInitialClosingDate" type="us-types:durationStringItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="PeriodForRegistrationStatementOfInitialClosingDate" id="omex_PeriodForRegistrationStatementOfInitialClosingDate" type="xbrli:durationItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="PeriodForRegistrationStatementSubjectToReview" id="omex_PeriodForRegistrationStatementSubjectToReview" type="us-types:durationStringItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="PeriodForRegistrationStatementToBeDeclaredEffective" id="omex_PeriodForRegistrationStatementToBeDeclaredEffective" type="us-types:durationStringItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="PeriodForWarrantTerm" id="omex_PeriodForWarrantTerm" type="xbrli:durationItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="PriorPeriodAccruedCompensationPaidByEquityInstruments" id="omex_PriorPeriodAccruedCompensationPaidByEquityInstruments" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="duration" xbrli:balance="debit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="ProceedsFromSaleOfSubsidiaryStock" id="omex_ProceedsFromSaleOfSubsidiaryStock" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="duration" xbrli:balance="debit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="ProjectTermLoanMember" id="omex_ProjectTermLoanMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="ReceiverMember" id="omex_ReceiverMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="RedemptionsOfSeniorConvertibleNotes" id="omex_RedemptionsOfSeniorConvertibleNotes" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="duration" xbrli:balance="credit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="RepaymentOfMortgageAndLoansPayable" id="omex_RepaymentOfMortgageAndLoansPayable" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="duration" xbrli:balance="credit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="RepublicProjectMember" id="omex_RepublicProjectMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="RevenueOwedToCertificateHolders" id="omex_RevenueOwedToCertificateHolders" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="instant" xbrli:balance="debit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="RevenueParticipationAgreementValue" id="omex_RevenueParticipationAgreementValue" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="instant" xbrli:balance="credit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="RevenueParticipationCertificatesPerUnitValue" id="omex_RevenueParticipationCertificatesPerUnitValue" type="us-types:perUnitItemType" abstract="false" xbrli:periodType="instant" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="ReversalOfAlternativeMinimumTaxMember" id="omex_ReversalOfAlternativeMinimumTaxMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="ReversalOfBadDebtProvision" id="omex_ReversalOfBadDebtProvision" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="duration" xbrli:balance="credit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="RiskFreeRatesUsingZeroCouponCountryTreasurySecurityRangeOfRates" id="omex_RiskFreeRatesUsingZeroCouponCountryTreasurySecurityRangeOfRates" type="num:percentItemType" abstract="false" xbrli:periodType="instant" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="ScheduleOfAllocationOfCashProceedsRelatedToAdditionalFinancingTableTextBlock" id="omex_ScheduleOfAllocationOfCashProceedsRelatedToAdditionalFinancingTableTextBlock" type="nonnum:textBlockItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="ScheduleOfAllocationOfCashProceedsToDerivativeComponentsAtTheirFairValuesTableTextBlock" id="omex_ScheduleOfAllocationOfCashProceedsToDerivativeComponentsAtTheirFairValuesTableTextBlock" type="nonnum:textBlockItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="ScheduleOfComponentsOfDerivativeLiabilitiesTableTextBlock" id="omex_ScheduleOfComponentsOfDerivativeLiabilitiesTableTextBlock" type="nonnum:textBlockItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="ScheduleOfConcentrationOfCreditRiskTable" id="omex_ScheduleOfConcentrationOfCreditRiskTable" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrldt:hypercubeItem"/>
  <element name="ScheduleOfInventoryTableTextBlock" id="omex_ScheduleOfInventoryTableTextBlock" type="nonnum:textBlockItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="ScheduleOfRevenueParticipationRightsTableTextBlock" id="omex_ScheduleOfRevenueParticipationRightsTableTextBlock" type="nonnum:textBlockItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="ScheduleOfShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsTableTextBlock" id="omex_ScheduleOfShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsTableTextBlock" type="nonnum:textBlockItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="SecuredCollateral" id="omex_SecuredCollateral" type="xbrli:integerItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="SeniorConvertibleDebitInterestSettledWithCommonStockIssuance" id="omex_SeniorConvertibleDebitInterestSettledWithCommonStockIssuance" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="duration" xbrli:balance="debit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="SeniorConvertibleNoteMember" id="omex_SeniorConvertibleNoteMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="SeniorConvertibleNotesMember" id="omex_SeniorConvertibleNotesMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="SeriesOneVotingSharesMember" id="omex_SeriesOneVotingSharesMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="SettlementOfVendorPayableWithSubsidiaryStock" id="omex_SettlementOfVendorPayableWithSubsidiaryStock" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="duration" xbrli:balance="debit" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="ShareBasedCompensationArrangementByShareBasedPaymentAwardExercisePriceCondition" id="omex_ShareBasedCompensationArrangementByShareBasedPaymentAwardExercisePriceCondition" type="xbrli:stringItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsIssued" id="omex_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsIssued" type="xbrli:sharesItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="SharesIssuedInConnectionWithSettlementOfAccountsReceivable" id="omex_SharesIssuedInConnectionWithSettlementOfAccountsReceivable" type="xbrli:sharesItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="SharesOfCommonStockIssuableUponExerciseOfWarrant" id="omex_SharesOfCommonStockIssuableUponExerciseOfWarrant" type="xbrli:sharesItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="SharesReceivedFromExchange" id="omex_SharesReceivedFromExchange" type="xbrli:sharesItemType" abstract="false" xbrli:periodType="instant" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="SharesReceivedFromUnconsolidatedEntities" id="omex_SharesReceivedFromUnconsolidatedEntities" type="xbrli:sharesItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="SharesUsedInComputationForEarningPerShareBasic" id="omex_SharesUsedInComputationForEarningPerShareBasic" type="xbrli:sharesItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="ShortTermInvestmentsMaturityPeriod" id="omex_ShortTermInvestmentsMaturityPeriod" type="xbrli:stringItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="SmmProjectLimitedLiabilityCompanyMember" id="omex_SmmProjectLimitedLiabilityCompanyMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="SsGairsoppaMember" id="omex_SsGairsoppaMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="StockOptionsWithExercisePriceOfFivePointZeroZeroMember" id="omex_StockOptionsWithExercisePriceOfFivePointZeroZeroMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="StockOptionsWithExercisePriceOfFourPointZeroZeroMember" id="omex_StockOptionsWithExercisePriceOfFourPointZeroZeroMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="StockOptionsWithExercisePriceOfOnePointSevenFourMember" id="omex_StockOptionsWithExercisePriceOfOnePointSevenFourMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="StockOptionsWithExercisePriceOfSevenPointZeroZeroMember" id="omex_StockOptionsWithExercisePriceOfSevenPointZeroZeroMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="StockOptionsWithExercisePriceOfThreePointFiveOneMember" id="omex_StockOptionsWithExercisePriceOfThreePointFiveOneMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="StockOptionsWithExercisePriceOfThreePointFiveThreeMember" id="omex_StockOptionsWithExercisePriceOfThreePointFiveThreeMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="StockOptionsWithExercisePriceOfThreePointFiveZeroMember" id="omex_StockOptionsWithExercisePriceOfThreePointFiveZeroMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="StockOptionsWithExercisePriceOfThreePointFourThreeMember" id="omex_StockOptionsWithExercisePriceOfThreePointFourThreeMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="StockOptionsWithExercisePriceOfThreePointFourZeroMember" id="omex_StockOptionsWithExercisePriceOfThreePointFourZeroMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="StockOptionsWithExercisePriceOfThreePointNineZeroMember" id="omex_StockOptionsWithExercisePriceOfThreePointNineZeroMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="StockOptionsWithExercisePriceOfThreePointTwoFiveMember" id="omex_StockOptionsWithExercisePriceOfThreePointTwoFiveMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="StockOptionsWithExercisePriceOfTwoPointEightNineMember" id="omex_StockOptionsWithExercisePriceOfTwoPointEightNineMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="StockOptionsWithExercisePriceOfTwoPointSevenFourMember" id="omex_StockOptionsWithExercisePriceOfTwoPointSevenFourMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="StockOptionsWithExercisePriceOfTwoPointSevenThreeMember" id="omex_StockOptionsWithExercisePriceOfTwoPointSevenThreeMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="StockOptionsWithExercisePriceOfTwoPointTwoZeroMember" id="omex_StockOptionsWithExercisePriceOfTwoPointTwoZeroMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="TermLoanMember" id="omex_TermLoanMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="TrancheOneMember" id="omex_TrancheOneMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="TrancheThreeMember" id="omex_TrancheThreeMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="TrancheTwoMember" id="omex_TrancheTwoMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="TwoZeroOneFourSharePurchaseOptionMember" id="omex_TwoZeroOneFourSharePurchaseOptionMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="WarrantAndSharePurchaseOptionDerivativesMember" id="omex_WarrantAndSharePurchaseOptionDerivativesMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="WarrantDerivativeMember" id="omex_WarrantDerivativeMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="WarrantGroupOneMember" id="omex_WarrantGroupOneMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="WarrantGroupThreeMember" id="omex_WarrantGroupThreeMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="WarrantGroupTwoMember" id="omex_WarrantGroupTwoMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="WarrantsAndOptionsMember" id="omex_WarrantsAndOptionsMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="WarrantsAttachedToSeniorConvertibleDebtMember" id="omex_WarrantsAttachedToSeniorConvertibleDebtMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="WarrantsAttachedToSeriesGPreferredStockMember" id="omex_WarrantsAttachedToSeriesGPreferredStockMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="WarrantsWithExercisePriceOfThreePointSixZeroMember" id="omex_WarrantsWithExercisePriceOfThreePointSixZeroMember" type="nonnum:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
  <element name="WeightOfSilverBullionRecovered" id="omex_WeightOfSilverBullionRecovered" type="num:massItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item"/>
</schema>
