Sunken Ghost Ship

The Sunken Ghost Ship is 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 Bullet Bills, Mines, Koopas, and a massive swarm of Disappearing Boo Buddies.

Trivia

 * The Super Mario World manual mentions that the Sunken Ghost Ship may have once been one of the Airships utilized by the Koopalings in Super Mario Bros. 3.
 * This is the only level in Super Mario World that has a Green ? Ball.