The Princess's Secret Slide

The Princess's Secret Slide is one of three secret levels in Super Mario 64 and Super Mario 64 DS, where Mario must simply ride a winding slide to the bottom, where two Power Stars can be found.

The entrance to the slide is on the first floor, atop the central staircase, and behind the star door labeled "1", meaning it will require 1 Power Star to enter. In the room behind the door are three (two in Super Mario 64 DS) identical stained glass windows with images of Princess Peach on them. The one on the right is the entrance to the slide. In the DS version, the room is expanded to hold the character doors but the slide itself remains the same and is still accessed via a picture of Peach in the same room. If Mario falls off, he will not lose a life, but will be sent back to the castle lobby. Like other secret levels, the player can lose a life by taking damage until it reaches zero. In this case, the only way to take damage is to jump from the first part of the slide to the second part of the slide, resulting in damage due to falling from heights. This is the only secret course that contains Blue Coins, and the only course that has no Red Coins mission.

The room that housed the entrance to the slide was redesigned in the DS version to also serve as character select and Rec Room entrance. But an early version of the room, based on the N64 version, can be found in the game's files. Also in the DS version, it is one of the four courses in VS Mode. The first star is at the start, the second at the middle, and the last three at the end.

First Star
Mario must ride the slide all the way to the bottom and hit the ! Block to collect the Power Star.

Second Star
This second Star will only appear if the player reaches the bottom of the slide in under 21 seconds. This Star will appear in front of the ! block that contained the first star.

Trivia

 * The tune that plays in the course is a variation of the Bob-omb Battlefield theme (also the main theme of the game), as well as Cool, Cool Mountain's music. This tune can also be heard in most other secret courses, in secret areas that involve a slide, and in other regular courses such as Rainbow Ride.
 * The music is also remixed in Super Smash Bros. Melee and Super Smash Bros. Brawl, as well as in Super Mario Galaxy 2 in the Tall Trunk Galaxy level "Tall Trunk's Big Slide", and in the Rolling Coaster Galaxy. Another remix can be heard in Paper Mario: Sticker Star in Bowser's Snow Fort, during the mine cart sections. Super Mario 3D World features another variation that plays while riding Plessie. The original version appears in Super Smash Bros. for Wii U. A remixed version appears as one of the selectable songs in Mario & Sonic at the Sochi 2014 Olympic Winter Games and Mario & Sonic at the Rio 2016 Olympic Games. A remix is also heard in Captain Toad: Treasure Tracker where it plays during part of the Coins Galore minigames.