<?xml version="1.0"?>
<ownershipDocument>
    <schemaVersion>X0201</schemaVersion>

    <documentType>4</documentType><periodOfReport>2003-11-20</periodOfReport>
    <issuer>
        <issuerCik>0000098222</issuerCik>
        <issuerName>TIDEWATER INC</issuerName>
        <issuerTradingSymbol>TDW</issuerTradingSymbol></issuer><reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001125826</rptOwnerCik>
            <rptOwnerName>LEONARD J WAYNE</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O ENTERGY CORPORATION</rptOwnerStreet1>
            <rptOwnerStreet2>639 LOYOLA AVENUE</rptOwnerStreet2>
            <rptOwnerCity>NEW ORLEANS</rptOwnerCity>
            <rptOwnerState>LA</rptOwnerState>
            <rptOwnerZipCode>70113</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
<isDirector>1</isDirector><isOfficer>0</isOfficer><isTenPercentOwner>0</isTenPercentOwner><isOther>0</isOther></reportingOwnerRelationship></reportingOwner><derivativeTable><derivativeTransaction><securityTitle><value>Stock Option (Right to Buy)</value><footnoteId id="F1"/></securityTitle><conversionOrExercisePrice><value>26.80</value></conversionOrExercisePrice><transactionDate><value>2003-11-20</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>M</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>5000</value></transactionShares><transactionPricePerShare><footnoteId id="F1"/></transactionPricePerShare><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><exerciseDate><value>2004-05-20</value></exerciseDate><expirationDate><value>2013-11-20</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>5000</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>5000</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></derivativeTransaction></derivativeTable><footnotes><footnote id="F1">Stock option granted under the Tidewater Inc. 2001 Stock Incentive Plan. The Plan pursuant to which the reported option was granted provides for tax withholding rights.</footnote></footnotes><remarks/><ownerSignature><signatureName>J. Wayne Leonard, By: Michael L. Goldblatt, Agent and Attorney-in-Fact</signatureName><signatureDate>2003-11-20</signatureDate></ownerSignature></ownershipDocument>
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X0201
4
2003-11-20
0000098222
TIDEWATER INC
TDW
0001125826
LEONARD J WAYNE
C/O ENTERGY CORPORATION
639 LOYOLA AVENUE
NEW ORLEANS
LA
70113
1
0
0
0
Stock Option (Right to Buy)
26.80
2003-11-20
4
M
0
5000
A
2004-05-20
2013-11-20
Common Stock
5000
5000
D
Stock option granted under the Tidewater Inc. 2001 Stock Incentive Plan. The Plan pursuant to which the reported option was granted provides for tax withholding rights.
J. Wayne Leonard, By: Michael L. Goldblatt, Agent and Attorney-in-Fact
2003-11-20