Exhibit
10.7





JOINDER
AGREEMENT


(Security
Agreement)





February
13, 2009





Re:
            Security
      Agreement dated as of November 11, 2008 (as amended, restated, or
      supplemented from time to time, the “Security
      Agreement”), executed by DEEP DOWN, INC., a Nevada corporation
      (“Borrower”),
      ELECTROWAVE USA, INC., a Nevada corporation (“Electrowave”),
      FLOTATION TECHNOLOGIES, INC., a Maine corporation (“FloTech”),
      MAKO TECHNOLOGIES, LLC, a Nevada limited liability company (“Mako”),
      and DEEP DOWN INC., a Delaware corporation (“DD
      Delaware,” and together with Borrower, Electrowave, FloTech, and
      Mako, each an “Existing
      Debtor” and, collectively, the “Existing
      Debtors”), for the benefit of WHITNEY NATIONAL BANK, a national
      banking association (“Lender”).





RECITALS





A.           Borrower
and Lender entered into that certain Credit Agreement dated as of November 11,
2008 (as amended by First Amendment to Credit Agreement dated December 18, 2008,
Second Amendment to Credit Agreement dated February 13, 2009, and as further
amended, restated, or supplemented, the “Credit
Agreement”).





B.           As
a condition precedent to extending credit to Borrower under the Credit
Agreement, Lender required that Electrowave, FloTech, Mako, and DD Delaware
execute that certain Guaranty dated as of November 11, 2008 (as amended,
restated, or supplemented from time to time, the “Guaranty”),
in favor of Lender.





C.           To
secure (i) the “Obligation” under, and as defined in, the Credit Agreement, and
(ii) the “Guaranteed Obligation” under, and as defined in, the Guaranty,
Existing Debtors executed the Security Agreement.





D.           DEEP
DOWN INTERNATIONAL HOLDINGS, LLC, a Nevada limited liability company (“New
Debtor”), was recently organized and is or will become a direct
wholly-owned subsidiary of Borrower.





E.           As
required under the Credit Agreement, New Debtor and Existing Debtors have
executed a Joinder Agreement (Guaranty) dated as of the date hereof, pursuant to
which New Debtor has become a “Guarantor” under the Guaranty.





F.           To
secure New Debtor’s obligations under the Guaranty, New Debtor and Existing
Debtors have agreed to execute this Joinder Agreement for the benefit of
Lender.





AGREEMENT





NOW THEREFORE, for good and valuable
consideration, the receipt and adequacy of which is hereby acknowledged, the
parties hereto agree as follows:








1.           To
secure the prompt, unconditional, and complete payment and performance of the
Obligation when due, New Debtor hereby pledges and assigns to Lender, and grants
to Lender a continuing security interest in all of its right, title and interest
in, to, and under the following, wherever located and whether now owned or
hereafter acquired or created by New Debtor:  all personal and fixture
property of every kind and nature including, without limitation, all goods
(including inventory, equipment and any accessions thereto), instruments
(including promissory notes), documents, accounts, accounts receivable, chattel
paper (whether tangible or electronic), deposit accounts, letter-of-credit
rights (whether or not the letter of credit is evidenced by a writing),
commercial tort claims, securities and all other investment property, supporting
obligations, any other contract rights or rights to the payment of money,
insurance claims and proceeds, all software, fixtures, vehicles (whether or not
subject to a certificate of title statute), leasehold improvements, and all
general intangibles (including all payment intangibles and trademarks and
patents).





2.           New
Debtor hereby (a) agrees to become a “Debtor” under the Security Agreement, and
(b) joins in, becomes a party to, and agrees to comply with and be bound by all
of the terms and conditions of the Security Agreement to the same extent as if
New Debtor were an original signatory thereto.  New Debtor shall
hereafter be jointly and severally liable for the performance of any and all
past, present and future obligations of any Debtor under the Security Agreement,
it being understood and agreed that any and all references in the Security
Agreement to “Debtor” or “Debtors” shall include New Debtor.





3.           New
Debtor acknowledges that (a) Lender has agreed to extend credit to Borrower for
the purposes set forth in the Credit Agreement, (b) it is receiving direct and
indirect benefits from each such extension of credit, (c) the obligations of the
“Debtor” or “Debtors” under the Security Agreement are the joint and several
obligations of each Debtor, (d) certain representations and warranties set forth
in the Security Agreement are in respect of it, and New Debtor hereby confirms
that each such representation and warranty is true and correct, and (e) certain
covenants set forth in the Security Agreement are in respect of it or shall be
imposed upon it, and New Debtor covenants and agrees to promptly and properly
perform, observe, and comply with each such covenant.





4.           Capitalized
terms used but not defined herein have the meanings given them in the Credit
Agreement.
















[Signature is on the following
page.]


2












IN
WITNESS WHEREOF, each of the undersigned has executed this Joinder Agreement
under seal as of the date first written above.











NEW
      DEBTOR:
              
              DEEP
      DOWN INTERNATIONAL HOLDINGS, LLC,
              a
      Nevada limited liability company
              
              
              By: /s/ Eugene L.
      Butler
              Eugene
      L. Butler
              Chief
      Financial Officer
              
              
              EXISTING
      DEBTORS:
              
              DEEP
      DOWN, INC.,
              a
      Nevada corporation
              
              ELECTROWAVE
      USA, INC.,
              a
      Nevada corporation
              
              FLOTATION
      TECHNOLOGIES, INC.,
              a
      Maine corporation
              
              MAKO
      TECHNOLOGIES, LLC,
              a
      Nevada limited liability company
              
              DEEP
      DOWN INC.,
              a
      Delaware corporation
              
              
              By: /s/ Eugene L.
      Butler
              Eugene
      L. Butler
              Chief
      Financial Officer of each of the foregoing
  companies












Signature
Page to Joinder Agreement
 (SecurityAgreement)