The main Island of The Spirit World.

(CLASSIFIED Information)  The Spirit World is the place where quads go after death. It is full of animal spirits and enlightened human spirits.  It is a massive world of islands that float in yellow fog. every island is covered in grass, rock, sand, and trees. Three types of trees grow here: Oak, Spirit, and Crystal Warp. 

The crystal warp tree is a vine that grows 4 meters off the ground and a purple crystal grows on it. If the crystal is touched by Spirit World citizens, they are warped back to Earth, in their spiritual tree.

One island, called, the Main Island, has a 300 meter tall hollow tree. Everyone lives in it, and trees grow IN it!