Behind the Waterfall

The Metal Cavern is a cave in Super Mario 64 that contains the Metal Cap's ! Switch. The cave is decorated with large glittering crystals and has a stream running through the middle. The water is moving very fast and can sweep Mario out the cave's one-way exit, the waterfall outside Peach's Castle. Upon entering the cave, Mario is automatically turned into Metal Mario and invulnerable to the stream's current. Quickly defeat the few Snufits guarding the Green ! Switch and press it. All the green ! Blocks in the game will activate, granting access to the Metal Cap.

Eight Red Coins are in the area, and several of them are just below a huge waterfall supplying the stream. The only way to reach them is with the Metal Cap.

The entrance is located in Hazy Maze Cave, behind the double doors in the underground lake.