Instructions
Play the Ballad of Gales song and warp to Windfall Island. Enter the schoolhouse during the day and talk to the teacher. She will ask you to go talk to the gang of kids outside.
Talk to the kids outside the schoolhouse. They will challenge you to a game of hide and seek. The kids will be hiding on top of the tree by the schoolhouse, behind the bomb shop, behind the stone on the cliff and by the town's gate.
Enter the schoolhouse and talk to the teacher again. She will thank you for talking to the children and give you a purple rupee. Go back outside and talk to the kids again. They will tell you about the teacher's love of joy pendants.
Talk to the teacher again and she will ask for 20 joy pendants. You should have at least 30 pendants at this point in the game, however if you don't, you can find more by fighting enemies and smashing pots. Give the teacher the joy pendants and she will give you the item "Cabana Deed."
Sail southeast to the private oasis at E-5. Walk up to the house and show the deed to the butler at the door. He will open the door and allow you to enter the cabana.
Take out your grappling hook and shoot it toward the wooden stake on the ceiling. This will cause the fire in the fireplace to go out. Enter the fireplace and jump down the hole hidden in the back. This will take you underneath the cabana.