Angular Isles
Angular Isles is located at E7. It has an Overworld Check, a secret cave, a Blue Chuchu, and a sunken treasure.
Checks
Peak
Original Item: Piece of Heart
Type: Island Puzzles
Push and pull blocks as required on the main island to reach the top. There, you'll find the chest, along with a Blue Chuchu.
Cave
Original Item: Silver Rupee
Type: Puzzle Secret Caves
Enter the secret cave on the small island. Solve the block puzzle to reach the intersection of the two beams of light at the top. Use the Mirror Shield to shine the light onto the transparent chest to spawn it in. Either Leaf down to the chest or Hookshot to it to claim your reward.
Sunken Treasure
Original Item: Piece of Heart
Type: Sunken Treasure
Open the treasure chart for Angular Isles and salvage up the treasure using the Grappling Hook. Without randomized charts, the chart for Angular Isles is Treasure Chart 15.