This is a glitch in Super Mario 64 DS. It is that game's version of the Dark World, but with one major difference- There is NO ESCAPE! To do this, perform Under the Castle Grounds. Then, make your way under the moat to below those four black boxes.Simply swim in, and you will suddenly be trapped under them! You have no way of breaking them, and you are not warped to the Invisible Cap stage, (well, it WAS invisible cap stage in the original...) no matter how high you jump! You are trapped, and the only way out is to exit the game. Wasn't that fun? :)
Why it works Edit
As you swim through the side, the game realizes you are on land, and you end up under the boxes. You cannot get warped to the secret stage, as that reqires breaking the boxes, and as this glitch isn't possible with Wario... You are hopelessly trapped for all eternity.
This glitch was discovered by Uberninja1337, and possibly some other people.