Island in the Sky is an island that was featured in The Clash of Triton. Triton was locked there in a cage by his father, Neptune. Neptune locked him there for 10,000 years until he learned to become a proper god. SpongeBob and Patrick went there to free Triton so Neptune could see him for his 5,000th birthday. SpongeBob had his best wedding clothes.
Much about the island is unknown or unexplored but many of it's features are shown. But there is a cage where Triton is trapped in with a lock on the cage door. Also there is a bus stop on the edge of the island where people can enter/exit the island. Even there is a phone booth right across from the cage.