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

    <documentType>4</documentType><periodOfReport>2003-10-29</periodOfReport>
    <issuer>
        <issuerCik>0000098222</issuerCik>
        <issuerName>TIDEWATER INC</issuerName>
        <issuerTradingSymbol>TDW</issuerTradingSymbol></issuer><reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001065094</rptOwnerCik>
            <rptOwnerName>DU MOULIN RICHARD T</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O TIDEWATER INC.</rptOwnerStreet1>
            <rptOwnerStreet2>601 POYDRAS ST., SUITE 1900</rptOwnerStreet2>
            <rptOwnerCity>NEW ORLEANS</rptOwnerCity>
            <rptOwnerState>LA</rptOwnerState>
            <rptOwnerZipCode>70130</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>26.17</value></conversionOrExercisePrice><transactionDate><value>2003-10-29</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>2004-04-29</value></exerciseDate><expirationDate><value>2013-10-29</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>Richard T. du Moulin, by Michael L. Goldblatt, Agent and Attorney-in-Fax</signatureName><signatureDate>2003-10-30</signatureDate></ownerSignature></ownershipDocument>
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X0201
4
2003-10-29
0000098222
TIDEWATER INC
TDW
0001065094
DU MOULIN RICHARD T
C/O TIDEWATER INC.
601 POYDRAS ST., SUITE 1900
NEW ORLEANS
LA
70130
1
0
0
0
Stock Option (Right to Buy)
26.17
2003-10-29
4
M
0
5000
A
2004-04-29
2013-10-29
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.
Richard T. du Moulin, by Michael L. Goldblatt, Agent and Attorney-in-Fax
2003-10-30