Karkat is a crabbing boat like on Deadliest Catch.
Aradia is a sailboat.
Tavros is a wooden dinghy, riddled with leaks.
Sollux is a biplane or whatever those planes with floaty boat landing gear things are.
Kanaya is a yacht, shiny and brand-new and incredibly luxurious inside.
Nepeta is a speedboat with a motor that breaks down a lot. Equius tows her back to the pier whenever she breaks down.
Vriska is a wooden pirate galleon boat thing.
Terezi is a jet ski.
Equius is an old tugboat, rusted and somewhat barnacle-encrusted but with a large and powerful engine.
Gamzee is a bright orange inflatable liferaft.
Eridan is an old German U-Boat.
Feferi is a high-tech submarine thing used for science.