In the Land of Lightning, there is a gigantic and ancient turtle that Kumogakure has cared for since its founding. It serves as a training ground for the Kumo ninja, and is described as a moving fortress. Its size is so great that it can host other large animals as well as other natural and man-made structures. It is considered to be the equivalent of Konoha's Forest of Death.

The turtle's shell, the "island", has an accumulation of plant life that has grown on it. Despite being described by the Great Toad Sage as a paradise, it is anything but that to humans, with signs of death and battle everywhere and large, ferocious animals populating the island. The Falls of Truth can also be found on the island. The island was protected by a Giant Squid, which attacked anything that approached, and a high-level barrier technique. In addition, the island can move, making it impossible to find without air reconnaissance.