Rusukaina

Rusukaina is an island in the Calm Belt that is to the northwest of Amazon Lily. It is a forty eight season island whose climate changes every week. There are several different species of dangerous animals on it. A country supposedly used to exist on this island, but its people could not survive against nature which made the land very dangerous and they all died out. According to Silvers Rayleigh, when Luffy arrived in the island, there were over 500 beasts living there he would not be able to defeat. Rayleigh took Luffy here to train him in the use of Haki for 2 years. On this island there is only one safe spot, near a tree that resembles a Daft Green from Merveille.

Trivia

 * "Rusukaina" means "Anybody home?"