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

    <documentType>4</documentType><periodOfReport>2003-10-24</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><nonDerivativeTable><nonDerivativeTransaction><securityTitle><value>Common Stock</value></securityTitle><transactionDate><value>2003-10-24</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>P</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>3000</value></transactionShares><transactionPricePerShare><value>26.75</value></transactionPricePerShare><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><postTransactionAmounts><sharesOwnedFollowingTransaction><value>4200</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></nonDerivativeTransaction><nonDerivativeTransaction><securityTitle><value>Common Stock</value></securityTitle><transactionDate><value>2003-10-24</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>P</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>300</value></transactionShares><transactionPricePerShare><value>26.71</value></transactionPricePerShare><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><postTransactionAmounts><sharesOwnedFollowingTransaction><value>4500</value><footnoteId id="F1"/></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></nonDerivativeTransaction></nonDerivativeTable><footnotes><footnote id="F1">In addition to shares of Common Stock for which Direct ownership is shown, 1,200 shares of Common Stock are owned by the children of the reporting person for which the reporting person disclaims beneficial ownership, and this report shall not be deemed an admission that the reporting person is the beneficial owner of the securities owned by his children for Section 16 or for other purposes.</footnote></footnotes><remarks/><ownerSignature><signatureName>Richard T. du Moulin by Michael L. Goldblatt, Agent and Attorney-in-Fac</signatureName><signatureDate>2003-10-24</signatureDate></ownerSignature></ownershipDocument>
[{"type": "4", "sequence": "1", "filename": "edgar.xml", "description": "PRIMARY DOCUMENT", "secsgml_size_bytes": 3593}]
X0201
4
2003-10-24
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
Common Stock
2003-10-24
4
P
0
3000
26.75
A
4200
D
Common Stock
2003-10-24
4
P
0
300
26.71
A
4500
D
In addition to shares of Common Stock for which Direct ownership is shown, 1,200 shares of Common Stock are owned by the children of the reporting person for which the reporting person disclaims beneficial ownership, and this report shall not be deemed an admission that the reporting person is the beneficial owner of the securities owned by his children for Section 16 or for other purposes.
Richard T. du Moulin by Michael L. Goldblatt, Agent and Attorney-in-Fac
2003-10-24