Bowser Castle 2 is one of the very many courses in Mario Kart: Super Circuit. It is the final course in the Flower Cup. Like most Bowser Castle levels in the Mario Kart series, there are several lava pits and Thwomps that act as obstructions in the course for the racers to dodge.
It later reappeared in the Banana Cup in Mario Kart DS. In this game, it appeared as the third in the cup itself. Not much differences except for the updated 3D textures and models. There is also the first jump which is now required for players to be in their regular form to make the first jump.