The Secret Aquarium
From the Super Mario Wiki
The Secret Aquarium is one of the secret courses in Super Mario 64 and Super Mario 64 DS. The entrance to the course is to the right of the painting into Jolly Roger Bay, through a small hole up above on the wall.
Layout and Mission
The Secret Aquarium is a large cubed room filled with water. There is no place for the player to surface for air, so they will have to collect Coins in order to avoid drowning. There are Yellow Coins in rings with Red Coins in the center of the rings and on the room's floor. The only Power Star to collect is the one that appears when the player collects all eight of the Red Coins around the aquarium. While not physically changed in Super Mario 64 DS, the course features music absent from the original game: the full percussion version of the Dire, Dire Docks theme.
Names in other languages