Super Mario 64 DS Glitches

Access Basement Area Without The Key
To make this glitch possible, the moat must not be drained and you must not have finished Bowser in the Dark World. To do it, you need to do the Underground Pool glitch and swim deep, but not too deep, under the ground and swim to the surface where you will be technically inside the castle. Now turn the camera so you can see the basement door and swim into it. The screen will go white and you will be in the basement, where you will be able to walk. You cannot pound the pillars, and going to the door that leads to the ground floor will just say that you need the key. The only way out is to enter one of the three accessible courses and choose Exit Course, which will take you to the castle lobby.