Vanish Cap Under the Moat (called Vanish Cap Switch Course in the message that appears when first entering) is a secret course in Super Mario 64 that is accessed through the moat outside the castle after the water has been drained. To do so, Mario must ground-pound the two pillars in the basement, then go out to the newly-exposed door. He will find a hole in the drained moat near the waterfall that will warp him to the course. It consists of a massive slope at the start, 8 Red Coins, several moving platforms, and the switch that activates the Vanish Cap when pressed on. The switch is located at the end of the level. If the player falls off, they will exit from a hole near the moat and not die.
In Super Mario 64 DS, the course was retitled The Secret Under the Moat and the blue ! Switch was removed.
There are two Power Stars in this level, with one being exclusive to the DS version.
8 Red Coins
The first four coins are located on the slide ledges of the start, while the other four are located on the moving platforms along the path to the ! Switch. After collecting all the red coins and pressing the switch, Mario will have to grab a Vanish Cap and go through the cage to collect the star.
In the DS version, the player can use either Mario or Wario to collect the red coins on the slide or moving platforms (though controlling Mario is generally easier). By using Luigi's Cap, Wario can use a power flower, in place of the Vanish Cap, and go through the cage to get the star.
Switch Star (DS only)
A new area was added across the chasm at the bottom of the slide. By turning into Mario, Wario can use a power flower to float to the new area. By activating the Star Switch on the platform, the Power Star will appear in the Star Sphere above. Wario can reach it by either floating upwards to it or by using wall-kicks.
- This is one of the only three secret levels in the DS remake that only one certain character can access, as only Wario can start the course because the entrance is covered under the black bricks, which only he can destroy. The others being Bowser in the Sky for Mario and Chief Chilly Challenge for Luigi.