Boaty is SpongeBob's boat. It is first seen in the episode No Free Rides. It was given to him at Mrs. Puff's House during the celebration thrown by Margaret and Harold SquarePants when SpongeBob got his driver's license from extra credit in that episode. Mrs. Puff has attempted to boatjack it. SpongeBob loves the boat a lot.
SpongeBob, despite the fact he does not have his driver's license, still keeps it in his garage, even though it was unfortunately desroyed in No Free Rides.