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

    <documentType>4</documentType><periodOfReport>2004-01-09</periodOfReport>
    <issuer>
        <issuerCik>0000098222</issuerCik>
        <issuerName>TIDEWATER INC</issuerName>
        <issuerTradingSymbol>TDW</issuerTradingSymbol></issuer><reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001197244</rptOwnerCik>
            <rptOwnerName>DICK STEPHEN W</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>0</isDirector><isOfficer>1</isOfficer><isTenPercentOwner>0</isTenPercentOwner><isOther>0</isOther><officerTitle>Executive Vice President</officerTitle></reportingOwnerRelationship></reportingOwner><nonDerivativeTable><nonDerivativeTransaction><securityTitle><value>Common Stock</value></securityTitle><transactionDate><value>2004-01-09</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>M</transactionCode><equitySwapInvolved>0</equitySwapInvolved><footnoteId id="F1"/></transactionCoding><transactionAmounts><transactionShares><value>450</value></transactionShares><transactionPricePerShare><value>22.25</value></transactionPricePerShare><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><postTransactionAmounts><sharesOwnedFollowingTransaction><value>7594</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></nonDerivativeTransaction><nonDerivativeHolding><securityTitle><value>Common Stock</value></securityTitle><postTransactionAmounts><sharesOwnedFollowingTransaction><value>2562</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>I</value><footnoteId id="F2"/></directOrIndirectOwnership><natureOfOwnership><value>By Trustee</value></natureOfOwnership></ownershipNature></nonDerivativeHolding></nonDerivativeTable><derivativeTable><derivativeTransaction><securityTitle><value>Employee Stock Option (Right to Buy)</value><footnoteId id="F1"/></securityTitle><conversionOrExercisePrice><value>22.25</value></conversionOrExercisePrice><transactionDate><value>2004-01-09</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>M</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>450</value></transactionShares><transactionPricePerShare><footnoteId id="F1"/></transactionPricePerShare><transactionAcquiredDisposedCode><value>D</value></transactionAcquiredDisposedCode></transactionAmounts><exerciseDate><footnoteId id="F3"/></exerciseDate><expirationDate><value>2004-08-16</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>450</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>3675</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></derivativeTransaction></derivativeTable><footnotes><footnote id="F1">Exercise of employee stock options granted under Tidewater Inc. 1975 Incentive Stock Option Plan.</footnote><footnote id="F2">Acquired on a periodic basis by Trustee of Tidewater 401(k) Savings Plan. Includes shares acquired for my account through November 30, 2003.</footnote><footnote id="F3">Exercisable in 3 annual increments beginning August 16, 1995,</footnote></footnotes><remarks/><ownerSignature><signatureName>Stephen W. Dick, by Michael L. Goldblatt, Agent and Attorney-in-Fact</signatureName><signatureDate>2004-01-13</signatureDate></ownerSignature></ownershipDocument>
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X0201
4
2004-01-09
0000098222
TIDEWATER INC
TDW
0001197244
DICK STEPHEN W
C/O TIDEWATER INC.
601 POYDRAS ST., SUITE 1900
NEW ORLEANS
LA
70130
0
1
0
0
Executive Vice President
Common Stock
2004-01-09
4
M
0
450
22.25
A
7594
D
Common Stock
2562
I
By Trustee
Employee Stock Option (Right to Buy)
22.25
2004-01-09
4
M
0
450
D
2004-08-16
Common Stock
450
3675
D
Exercise of employee stock options granted under Tidewater Inc. 1975 Incentive Stock Option Plan.
Acquired on a periodic basis by Trustee of Tidewater 401(k) Savings Plan. Includes shares acquired for my account through November 30, 2003.
Exercisable in 3 annual increments beginning August 16, 1995,
Stephen W. Dick, by Michael L. Goldblatt, Agent and Attorney-in-Fact
2004-01-13