From a bird’s-eye view, Shark Island looks like a giant shark. This relatively small island features four switches and a hole surrounded by fire.
Silver Rupee (via Treasure Chart #16)
Find and open Treasure Chart #16 (on the Sea Platform in Seven-Star Isles [F1]) to pull a chest from the Great Sea near Shark Island. The chest contains a Silver Rupee.
Silver Rupee (via Secret Cave)
If you have the Iron Boots and the Skull Hammer, you can activate all four switches (within a time limit) and lower the flames around the island’s hole, which leads to a Secret Cave.
First cut down any saplings in the way of the switches. A clear path to each switch saves time. Then head to the “tail” of the island and ready your Skull Hammer and Iron Boots. Stand on top of the switch here and activate it by equipping the Iron Boots. Immediately unequip the Iron Boots and run to the white, diamond-shaped switch on the other side of the island, drawing your sword as you go.
Whack the diamond-shaped switch with your sword and then jump onto the nearby pressure switch to activate it as well. Now jump down to the peglike switch, lock on to it, and put the hammer down. An updraft appears next to the island and the ring of flames disappears, allowing you to enter the Secret Cave.
Inside, you face a tough battle. Moblins, Darknuts, and several other enemies come at you in mixed waves. If you defeat them all, a chest with a Silver Rupee appears.
Blue ChuChu
Activating all four switches on this island creates an updraft nearby. Use this updraft to reach the highest part of the island, where you find a Blue ChuChu. Head to the “tail” of the island where the Iron Boots switch is located, and set the wind to blow southeast. Use the Deku Leaf to glide into the updraft. Be prepared to battle the wind.
High in the air, go with the wind and head for the highest area of the island. Defeat the Blue ChuChu found there and collect its Blue Chu Jelly.