Battle Course 2 (SNES)
From the Super Mario Wiki
Battle Course 2 is the second battle course of Super Mario Kart, using the Koopa Beach tileset. Its form is a square as the other battle courses, and has L shaped and square holes on it. However, each L and block has shallow water in it, and there is little chance the player can fall into it.
Although they didn't appear in Mario Kart: Super Circuit, tilemaps and minimaps exist for all four of the Battle Courses from Super Mario Kart. These could have been used as placeholders before the new ones were completed, or it may have been possible to unlock these courses like the tracks at one point. Unlike all other tracks and battle courses in the game, which are stored in chunks, these are each stored in one piece, as in Super Mario Kart.