Rock Spire Isle (B3 on the map) is one of the 49 islands featured in The Legend of Zelda: The Wind Waker for the GameCube. It is one of the smaller islands, though nevertheless it has plenty of sidequests. Out in the sea are three Sea Platforms. The only noteworthy reward you can obtain by defeating the enemies found on top of the Sea Platforms is an Orange Rupee. Also found at sea are two Cannon Boats. Destroy them both to claim another Orange Rupee and Piece of Heart #23.
One of Beedle's Shop Ships are also around here, and you can also snag quite a few goodies as well, including an Empty Bottle, a Piece of Heart #22, and Treasure Chart #4. On the island you can kill a Blue ChuChu and collect its jelly and find Treasure Chart #37.