Genbu

Genbu, more commonly known as the Island Turtle, is a gigantic and ancient domesticated turtle that resides in the Land of Lightning. Since Kumogakure's founding they have cared for Genbu who has in turn serves as a training ground for the shinobi. Genbu is described as a moving fortress whose 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 Konohagakure's Forest of Death.