Gale Isle is the entrance to the Wind Temple in The Wind Waker, but the entrance is blocked by a great wind that pushes Link away. To enter the cave, Link must obtain the Iron Boots from Ice Ring Isle to get close to the stone that is blowing the wind, then smash it using the Skull Hammer. Inside, Link will find a large stone tablet, teaching him the Wind God's Aria. Link must show this melody to Makar in order to gain entrance to the main temple.
Fishman's hint on Gale Isle:
Are you thinking you want to get into that cave, small fry? The one that's protected by the crazy winds on that island? Heh heh heh! OK, then. Let me tell you a little secret... If you go five squares south and one square east from here, you'll reach Ice Ring Isle, where you'll find an item that will make you as heavy as stone! If you get that item, you won't have to worry about getting blown over by winds!
Trivia
- In The Legend of Zelda: The Wind Waker|The Wind Waker's sequel, Phantom Hourglass, a boss named Cyclok bears a striking resemblance to the statue that creates the wind on the island.