Bowser in the Sky

Bowser in the Sky is the third and final Bowser stage in Super Mario 64 and Super Mario 64 DS, and is the last level of the games. Mario travels through platforms in the sky until he reaches a Warp Pipe leading to a final fight against Bowser to save Princess Peach and the Toads in Mushroom Castle. 70 Power Stars (80 in Super Mario 64 DS) are required to open the Big Star Door on the third floor and reach the top of the endless stairs, or else the staircase will loop endlessly. However, there is a glitch in the N64 version that can be used to get up the stairs without the required stars.

Bowser in the Sky is one of the three levels in Super Mario 64 DS that only a certain character can access (the others being Chief Chilly Challenge for Luigi and The Secret Under the Moat for Wario), as Bowser will only allow Mario to enter this level. Even if the player has more than 80 Stars or any character enters through the Big Star Door other than Mario, they will still be brought to the endless stairs.

Layout
The stage begins with Mario landing on a large arrow-shaped platform, signifying the direction he's supposed to go. Next are a few platforms arranged like a set of stairs, with the final one having a moving platform slide out of it which can push Mario off the platform and into the abyss below if the player is not careful. At the top of the platforms is a block that can be pushed to reach a Red Coin. After the stair platforms is a turning platform that will turn based on where Mario is standing, dropping him out of the level if he remains in place for too long. Afterward is a large ramp that Mario can run up to reach a bend that leads into a spinning platform; in the DS version of the game, this platform holds the Star Sphere. The next bend leads toward a Ferris wheel-esque spinning set of platforms, followed by a small platform with a Whomp on it, a ledge with a Keronpa Ball, and finally an area with a Chuckya; all of which are positioned above a large platform. Afterward is a platform leading to a set of stairs that will activate upon pressing the Purple Switch.

At the top of the stairs is a large, bending platform with a few flamethrowers and Coins, along with a Red Coin at the top. At the end of this bending platform is a lift that will carry Mario through a series of platforms they need to jump over, with one of them containing a Spinning Heart the player can use to recover Mario's health. Once the lift reaches the end of its rail, it will turn around and head back to its original position, or if Mario remains off of it for a certain amount of time, it'll warp back to its original position. After the lift are two spinning platforms containing a Keronpa Ball, Bob-ombs, and Amps, with the back platform having a pole for Mario to climb and reach the next area.

By climbing the pole, Mario can reach a platform with two Goombas and two sliding platforms that bridge the gap between them. After the bending stone path beyond those are two Ferris wheel platforms Mario needs to jump between to reach the final platform. The final platform contains a trio of Goombas, some columns, and a Spinning Heart, though a strong gust of wind will constantly be pushing Mario back. The Warp Pipe at the end of the stage will take Mario to the final fight with Bowser.

Bowser Battle
While the method of defeating Bowser is similar to the previous fights, there are many differences between Bowser's attacks and the stage. Unlike the previous battles when the player had four mines (eight in the remake), this battle has five mines. When Bowser slams the ground, shockwaves will appear, and they'll damage Mario if he touches them. He retains the fire attacks from the previous battles and can also breathe a stream of fire into the air, which will fall back down as several fireballs. The last difference is that Bowser has to take damage from three mines before admitting defeat; when Bowser takes damage from two mines, he'll shake the battlefield, causing it to form a star-like shape, and the third throw will require much more power and timing than the first two. Additionally, each time Bowser is damaged, it becomes easier for Mario to grab Bowser's tail without having to bait him into performing the charge attack. After the third hit, Bowser will give Mario the Jumbo Star. When he touches it, he acquires the Wing Cap, allowing him to fly and land in the castle grounds, where Peach and two Toads (Luigi, Wario, and Yoshi in the DS version) are waiting for him. Mario will release Peach from above the door entrance, who bakes a cake for her heroes, and then the credits roll.

Missions
As with the previous Bowser levels, a Power Star can be obtained by collecting the eight Red Coins found throughout the level. The Power Star will then appear behind the Warp Pipe that leads to Bowser.

Star 2 (DS only)
Below the first set of platforms that rotate much like a Ferris wheel is a large stone platform. At one end is a Star Switch. Upon pressing it, the player must backtrack to the Star Sphere on the spinning platform from earlier to collect the Power Star.

Secrets

 * The statues before the pipe at the end of the level show a depiction of Mario jumping over a Fireball near Bowser, in the old Super Mario Bros. style.
 * Like the other Bowser stage Stars, the secret Stars in this level are shown under the "Castle Secret Star" count.
 * Upon his defeat, Bowser's message to the player will differ depending on whether or not all the game's Power Stars have been collected:

Trivia

 * Even though seven Goombas are seen in this level, there is actually an eighth Goomba in the N64 version, but its spawn point is off the edge of the platform. This results in the Goomba appearing at the very bottom of the level for a single frame and then disappearing. This makes the coin inside of said Goomba impossible to collect. The eighth Goomba was removed in the DS version.
 * In the DS version, this is the only time when Bowser mentions Mario by his name.