A magical floating island that came into being after the Master Emerald's magical energy started flowing through some of the land in the southwest of the Great Plains.
It is now where the Master Emerald sleeps, guarded by Knuckles The Echidna. It is also home to Tails and his workshop.
Due to the influence of the Master Emerald, many magical creatures and mutated animals have been seen on this island, as well as many plantlife taking on a completely different form. It is unknown what other things the Master Emerald has done to this floating fortress, but it can be assumed there's much worse.