From the Super Mario Wiki
Chocolate Island is a mountainous island located in the southeastern part of Dinosaur Land that serves as the sixth world in the game Super Mario World. The island is named after its chocolate-brown coloring, although upon activating Autumn mode, it will turn green instead (i.e. mint chocolate). Instead of lava, some levels have boiling hot mud (a reference to hot chocolate or hot cocoa). As levels are beaten, many of the small mountains covering the area are leveled to clear new paths across the island. This gradually gives the player access to more stages.
Part of Chocolate Island is featured in half of the Mario Kart series. Choco Mountain from Mario Kart 64 and later Mario Kart DS could be part of Chocolate Island. Also, in Super Mario Kart and Mario Kart: Super Circuit, there are two courses called Choco Island 1 and Choco Island 2 respectively. In Mario Kart DS, Choco Island 2 returned as a retro track.
Except for Chocolate Secret, which is located underground near the Valley of Bowser and is accessible via Warp Pipe, all these levels are found on Chocolate Island. Levels that are marked with an asterisk (*) features another exit.
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