Head to the right until you find a small house, then head inside. Turn on the teleporter and a cutscene will begin, congratulating you on all your help on the island. The crisis is over!
You're free to travel anywhere else on the island you wish. When you're ready, travel back to the Observatory, where Curly and Balrog are waiting.
Speak with Curly. If you agree that you're done on the island, you'll both fly away with Balrog, and the credits will roll.