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<!-- RR Donnelley Xcelerate Taxonomy Schema, based on XBRL 2.1  http://www.rrdonnelley.com/ -->
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<!-- Round: 6 -->
<!-- Creation date: 2014-08-07T14:04:26Z -->
<!-- Copyright (c) 2005-2013 R.R. Donnelley & Sons Company All Rights Reserved. -->
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        <link:definition>112 - Disclosure - INVESTMENTS IN UNCONSOLIDATED ENTITIES</link:definition>
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        <link:definition>113 - Disclosure - INCOME TAXES</link:definition>
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        <link:definition>124 - Disclosure - INCOME TAXES (Tables)</link:definition>
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        <link:definition>125 - Disclosure - MORTGAGE AND LOANS PAYABLE (Tables)</link:definition>
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        <link:definition>126 - Disclosure - DERIVATIVE FINANCIAL INSTRUMENTS (Tables)</link:definition>
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        <link:definition>127 - Disclosure - DEFERRED INCOME AND REVENUE PARTICIPATION RIGHTS (Tables)</link:definition>
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        <link:definition>128 - Disclosure - Summary of Significant Accounting Policies - Additional Information (Detail)</link:definition>
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        <link:definition>129 - Disclosure - Summary of Significant Accounting Policies - Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share For in The Money Potential Common Shares (Detail)</link:definition>
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        <link:definition>130 - Disclosure - Summary of Significant Accounting Policies - Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share For Out of Money Potential Common Shares (Detail)</link:definition>
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        <link:definition>131 - Disclosure - Summary of Significant Accounting Policies - Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share For Out of Money Potential Common Shares (Parenthetical) (Detail)</link:definition>
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        <link:definition>132 - Disclosure - Summary of Significant Accounting Policies - Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share, Convertible Preferred Stock (Detail)</link:definition>
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        <link:definition>133 - Disclosure - Summary of Significant Accounting Policies - Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share, Unvested Restricted Stock Awards (Detail)</link:definition>
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        <link:definition>134 - Disclosure - Summary of Significant Accounting Policies - Reconciliation of Numerators and Denominators used in Computing Basic and Diluted Net Income Per Share (Detail)</link:definition>
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        <link:definition>136 - Disclosure - Accounts Receivable - Summary of Accounts Receivable (Detail)</link:definition>
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        <link:definition>137 - Disclosure - Accounts Receivable - Additional Information (Detail)</link:definition>
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        <link:definition>141 - Disclosure - Income Taxes - Additional Information (Detail)</link:definition>
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        <link:definition>142 - Disclosure - Income Taxes - Schedule of Change in Valuation Allowance (Detail)</link:definition>
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        <link:definition>143 - Disclosure - Commitments and Contingencies - Additional Information (Detail)</link:definition>
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        <link:definition>144 - Disclosure - Mortgage and Loans Payable - Schedule of Consolidated Debt (Detail)</link:definition>
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        <link:definition>145 - Disclosure - Mortgage and Loans Payable - Schedule of Consolidated Debt (Parenthetical) (Detail)</link:definition>
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        <link:definition>146 - Disclosure - Mortgage and Loans Payable - Additional Information (Detail)</link:definition>
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        <link:definition>147 - Disclosure - Mortgage and Loans Payable - Schedule of Allocation of Cash Proceeds to Derivative Components at their Fair Values (Detail)</link:definition>
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  <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="MarineServicesObligationsDeferredRevenue" id="omex_MarineServicesObligationsDeferredRevenue" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="duration" xbrli:balance="credit" 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="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="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="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="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="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="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="StockOptionsWithExercisePriceOfThreePointThreeZeroMember" id="omex_StockOptionsWithExercisePriceOfThreePointThreeZeroMember" 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="TermLoanMember" id="omex_TermLoanMember" 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="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="WarrantsWithExercisePriceOfTwoPointFourFourMember" id="omex_WarrantsWithExercisePriceOfTwoPointFourFourMember" 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>


