The Underwater Heartbreaker is a blue tandem bicycle with two pedals, two clam seats, and streamers on the handles. It has propellers instead of wheels. It also has a front headlight and a raccoon's tail attached to the back of the bike. Later on, SpongeBob connects a child's trolley to the bike to carry Mr. Krabs.
Role in episode
When SpongeBob, Patrick, and Mr. Krabs decide to go on a "wild and crazy" trip to town, SpongeBob mentions the name of his bike and it being "the most powerful chick magnet in town." Mr. Krabs' expectations of a hot rod boatmobile are dashed when the transport is revealed to be said bike, and comments about it being more of a "chick repellent."
Later on, SpongeBob and Patrick pedal towards The Wash! with Mr. Krabs riding on a connected trolley. A teenage fish and his girlfriend drive their customized boatmobile beside the bike, and as an insult, the fish calls them "lost." SpongeBob shows him his compass, then the hot rod fish calls them dorks and drives away.