-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
Originator-Key-Asymmetric:
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 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 WbK6rIf2OmDXK21dnS/z6fy6olS5dcObsH5S4r6HlGL90kI+Ay8fDEi8gxnzSUyU
 6GFFEGsRAXiDlUunEPYlNg==

<SEC-DOCUMENT>0001181431-03-013552.txt : 20030709
<SEC-HEADER>0001181431-03-013552.hdr.sgml : 20030709
<ACCEPTANCE-DATETIME>20030709171905
ACCESSION NUMBER:		0001181431-03-013552
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20030707
FILED AS OF DATE:		20030709

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			DIVERSA CORP
		CENTRAL INDEX KEY:			0001049210
		STANDARD INDUSTRIAL CLASSIFICATION:	SERVICES-COMMERCIAL PHYSICAL & BIOLOGICAL RESEARCH [8731]
		IRS NUMBER:				223297375
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		4955 DIRECTORS PLACE
		CITY:			SAN DIEGO
		STATE:			CA
		ZIP:			92121
		BUSINESS PHONE:		858-526-5000

	MAIL ADDRESS:	
		STREET 1:		4955 DIRECTORS PLACE
		CITY:			SAN DIEGO
		STATE:			CA
		ZIP:			92121

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			BAUM WILLIAM H
		CENTRAL INDEX KEY:			0001231857

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-29173
		FILM NUMBER:		03780682

	BUSINESS ADDRESS:	
		STREET 1:		C/O DIVERSA CORP
		STREET 2:		4955 DIRECTRORS PL
		CITY:			SAN DIEGO
		STATE:			CA
		ZIP:			92121
		BUSINESS PHONE:		8585265106

	MAIL ADDRESS:	
		STREET 1:		C/O DIVERSA CORP
		STREET 2:		4955 DIRECTORS PL
		CITY:			SAN DIEGO
		STATE:			CA
		ZIP:			92121
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>rrd12813.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>
    <schemaVersion>X0101</schemaVersion>

    <documentType>4</documentType>
<periodOfReport>2003-07-07</periodOfReport>
<notSubjectToSection16>0</notSubjectToSection16>
    <issuer>
        <issuerCik>0001049210</issuerCik>
        <issuerName>DIVERSA CORP</issuerName>
        <issuerTradingSymbol>DVSA</issuerTradingSymbol></issuer>
<reportingOwner>
<reportingOwnerId>
            <rptOwnerCik>0001231857</rptOwnerCik>
            <rptOwnerName>BAUM WILLIAM H</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>  </rptOwnerStreet1>
            <rptOwnerStreet2>  </rptOwnerStreet2>
            <rptOwnerCity>  </rptOwnerCity>
            <rptOwnerState>  </rptOwnerState>
            <rptOwnerZipCode>  </rptOwnerZipCode>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
<isDirector>0</isDirector>
<isOfficer>1</isOfficer>
<isTenPercentOwner>0</isTenPercentOwner>
<isOther>0</isOther>
<officerTitle>Sr. V.P., Business Development</officerTitle>
<otherText></otherText></reportingOwnerRelationship></reportingOwner>
<nonDerivativeSecurity>
<securityTitle>
<value>Common Stock</value></securityTitle>
<transactionDate>
<value>2003-07-07</value></transactionDate>
<transactionCoding>
<transactionFormType>4</transactionFormType>
<transactionCode>S</transactionCode>
<equitySwapInvolved>0</equitySwapInvolved>
<footnoteId id="F1"/></transactionCoding>
<transactionTimeliness>
<value></value></transactionTimeliness>
<transactionAmounts>
<transactionShares>
<value>10000</value></transactionShares>
<transactionValue>
<value>10.0000</value></transactionValue>
<transactionAcquiredDisposedCode>
<value>D</value></transactionAcquiredDisposedCode></transactionAmounts>
<postTransactionAmounts>
<sharesOwnedFollowingTransaction>
<value>135536</value></sharesOwnedFollowingTransaction></postTransactionAmounts>
<ownershipNature>
<directOrIndirectOwnership>
<value>D</value></directOrIndirectOwnership>
<natureOfOwnership>
<value></value></natureOfOwnership></ownershipNature></nonDerivativeSecurity>
<footnotes>
<footnote id="F1">The sales reported on this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on June 12, 2003.</footnote></footnotes>
<ownerSignature>
<signatureName>Karin Eastham, Attorney-in-fact</signatureName>
<signatureDate>2003-07-09</signatureDate></ownerSignature></ownershipDocument>


</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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