Collect 10 Rocket Car Parts.
Well, friend, if Pozzik wants you to have your own boat, the first thing we're going to need is parts. Now guess who gets to go get them?
<Razzeric smiles as he points downward and then grabs you a spare diving helm and flippers.>
I'm afraid so, <name>. You get to go down into the deeps and salvage what rocket car parts you can find at the Raceway Ruins.