Bowser in the Dark World

"Bwa ha ha ha! You've stepped right into my trap, just as I knew you would! I warn you, "Friend," watch your step!"

- Bowser

Bowser in the Dark World, also simply called the Dark World, is the first Bowser level in Super Mario 64 and Super Mario 64 DS. It is a puzzle-like world with many traps and enemies, with the background displaying a massive dark cavern with sickly green stone spires protruding from the ground and ceiling. The trapdoor entrance is behind the Big Star Door on the mezzanine of the main floor of the Mushroom Castle. Eight Power Stars (12 in the DS remake) are needed to open this door.

In the corridor before the player enters the level, a painting that depicts Princess Peach is seen on the far wall. As the player walks closer, the painting will become a picture of Bowser, and a trapdoor will open in the ground, sending the player into the level. The painting is not able to be reached, as there is an invisible wall between the player and the painting.

Layout
The first section of the level is fairly straightforward. There will be a single green block followed by a flame thrower. Two moving pyramid-shaped platforms join onto a tall stone platform. The blue route is safer, but it is too steep for Mario to run up normally. The stone route is longer and flatter and has coins, but there is a flame thrower at the turn of it. More moving platforms lead to the next section of the level.

Next is a wooden octagonal platform with three Goombas awaiting Mario, as well as a yellow ! Block in the middle containing a 1-Up Mushroom. Connected to the platform is a wooden bridge linking to a path made out of a type of green stone. Six unbreakable crystals are stuck in the path, four of which are being circled by Amps. At the end of the path is a large stone cube with a yellow rectangular block sliding in and out of it and with a yellow ! Block containing three coins floating above it. Two sets of circling platforms will lead Mario to the final section of the level before the Bowser fight.

The next platform contains a single Goomba. To the left of the platform is a narrow path to a large circular platform containing coins, a 1-Up Mushroom, and an Amp. To the right of the base platform are two tilting purple platforms. Behind them, Mario can collect two 1-Up Mushrooms, and on the overhanging platforms, he can collect another two. There are two Goombas on a stone block after the seesaws, after which Mario must climb up some stone platforms to hit a Purple Switch, which activates a staircase that leads Mario to the Warp Pipe to Bowser. A signpost in front of the pipe has a message from Princess Peach warning Mario of attacks Bowser has and telling him how to defeat him.

Bowser battle
Once Mario enters the pipe, Bowser will show up, saying that Princess Peach is not in the Dark World. Bowser will attack using his trademark fire breath in stream, which can burn Mario. He can also jump up and shake the ground if Mario is too far away, stunning Mario if he is not in the air. To defeat Bowser, Mario must grab him by his tail, twirl him around to build up momentum, and then throw him into one of the four Floating Mines available (eight in Super Mario 64 DS). Upon Mario doing so, Bowser will admit defeat and disappear, leaving Mario with the Big Key to the Mushroom Castle's basement.

8 Red Coins
Eight Red Coins can be found throughout this level, many of which are difficult to obtain due to the fact that there are many gaps and narrow bridges in the course. The locations of the Red Coins are as follows:
 * Two on top of blocks that appear upon activation of a Purple Switch (In the DS remake, one of the coins is moved to near the starting platform.)
 * Next to the third crystal in the second section
 * Next to the stone cube, obtained when the yellow block protrudes out the side
 * In the far left corner of where two platforms circle each other
 * Next to the pin on an octagonal platform to the left of the start of the third section
 * Behind the second seesaw
 * Above the far left platform that overhangs the tilting platforms

Upon Mario collecting all the Red Coins, the Power Star will appear near the Warp Pipe that leads to Bowser.

Switch Star (DS only)
In Super Mario 64 DS, a Star Switch is placed next to the Warp Pipe leading to Bowser. Upon Mario pressing it, the Power Star will appear in a Star Sphere on one of the ledges below. The player has to go down the stairs and across the platforms above the seesaws to reach the Power Star before the timer runs out.

Music
The stage music is the same as in Bowser in the Fire Sea and Bowser in the Sky, with "Koopa's Road" as the name of the track being used for the course (but not while Bowser is fought). This music is reused for the Bowser stages in Super Mario Galaxy and Super Mario Galaxy 2. A remixed version is also available as a track that can be played during events in Mario & Sonic at the Olympic Winter Games and Mario & Sonic at the London 2012 Olympic Games.