GBA Bowser's Castle 2

Bowser's Castle 2 is the fourth course of the Flower Cup in Mario Kart: Super Circuit. Its obstacles are falling Thwomps and thin rectangular gaps in the floor that make drivers fall into the lava below. The track is also notable for its jumping ramps; similar to those found in newer installments (after Mario Kart DS) which allows racers to perform Tricks. A large statue of Bowser can be seen in the background. Prior to the release of Mario Kart Tour, it was named Bowser Castle 2.

Course layout
After the start, there is one sharp U-turn to the right. After a long straight piece there is a swing curve right-left with a Thwomp. After another straight piece and turning left, there is a grate bridge with three lava pits and a turn to the left, where there is another Thwomp and turn to the left. Then there is a section with a large lava pit and multiple gaps with Lava Bubbles jumping out. Afterwards, there is a turn to the right onto another grate bridge with more lava pits and ramps and a curve right near two Thwomps and the finish line.

Mario Kart DS
This course returns in Mario Kart DS as the third course in the Banana Cup. The layout of the course remains unchanged from the previous iteration, except with its enhanced 3D graphics and all the ramps now encompass Dash Panels. If a racer is shrunk by a Lightning, they cannot complete the first jump necessary for completing this course and will fall to the lava. Missions 4-5 and 5-4 take place on this course. In 4-5, the player has to collect 15 coins without getting squished by a Thwomp, and in 5-4, the player has to drive through 10 numbered gates in order. The course has never been available in Wi-Fi.

Mario Kart Tour
The course reappears once more in Mario Kart Tour. It was added into the game at the start of the Hammer Bro Tour alongside SNES Donut Plains 1, which was also last remade in Mario Kart DS. Though the standard layout is largely the same, there are now Barrel Bombs that are in certain areas, and some of the lava pits are smaller or absent. The platform directly after the first jump has a slightly different layout. It now uses the background of GBA Bowser's Castle 1. This course is a favorite of Ice Bro, Fire Bro, Monty Mole, Dry Bowser, King Bob-omb, Dry Bones (Gold), and Shy Guy (Ninja). It can also be a favorite of King Boo (Luigi's Mansion) if he is at level 3, and King Boo and Fire Rosalina if they are at level 6. Like other courses in the game, Bowser's Castle 2 has a reverse variant, a trick variant and a reverse and trick variant, referred to as Bowser's Castle 2R, Bowser's Castle 2T and Bowser's Castle 2R/T respectively. The former two were introduced alongside the normal variant in the Hammer Bro Tour, while the latter was introduced in the 2020 Trick Tour. The reverse and trick variant has a shortcut that contains many Thwomps, which are blocking the shortcut route.

Unlike most courses in the game, this course reuses Mario Kart 7's arrangement for GBA Bowser's Castle 1, instead of the original music from Mario Kart: Super Circuit.

For this course's tour appearances, see List of GBA Bowser's Castle 2 tour appearances in Mario Kart Tour.

Mario Kart DS

 * Instruction booklet bio: "This course appeared in Mario Kart: Super Circuit™ for the Game Boy Advance™. It's a flat course, but the lava trenches all over make it really dangerous."
 * European website bio: "Tight right-angled turns abound on Bowser's turf, as you contend with angry Thwomps threatening to squash your kart into a pancake, make daring boost-assisted leaps over lava pits, and cut corners mere millimetres away from flames hotter than Bowser's breath."

Mario Kart Tour

 * Mario Kart Tour Twitter: "Stay on course or you'll take a dip in the lava in Bowser's Castle 2. You'll want to keep an eye out! The path to victory is lined with Thwomps and Barrel Bombs. Keep your wits sharp as you take on Bowser's most fiendish course yet!"