Sunken Ghost Ship

A wrecked ship in Super Mario World that serves as a gate to the Valley of Bowser. After defeating Wendy O. Koopa, Mario has to swim through this ship in order to make the doorway to World 7 come out of the sea. On board the ship are some Bill Blasters, Floating Mines, Koopas, and a massive swarm of Disappearing Boo Buddies.

It's one of the Koopa Kids Airships from Super Mario Bros. 3. Probably Larry Koopa's because his castle is in the Valley of Bowser.

In Super Mario RPG
Another Sunken Ship appears in Super Mario RPG: Legend of the Seven Stars. This ship supposedly sunk when the giant Blooper, King Calamari attacked it. Before the ship sank completely the crew managed to seal Calamari in the treasure room.

The upper portion of this ship is filled with undead enemies which are no doubt the ghost's of the ship's ill fated crew. There are also several puzzle rooms in this portion. While the ship was underwater the crew sranded on the upper part made several puzzles and riddles, that when solved would reveal part of the password needed to open the treasure room.

The lower portion of the ship is almost completely submerged and filled with territoryle sea creatures. This portion of the ship is ruled by the infamous pirate shark Jonathan Jones and his crew.