Fire Mountain

The is an island in.

Features and Overview
The island is a violent volcano one sector south of Dragon Roost Island. If Link were to set foot on the island while the volcano is active, he will instantly burn as if he fell into lava. After meeting with the Fairy Queen on Mother & Child Isles, Link may fire an Ice Arrow at the flames protruding from the island. These flames will freeze, and Link will have five minutes in order to complete the island before it begins to erupt again.

After cooling the island, the young hero must scale the rock face and make his way to the volcano's peak, where there is a small cavern drop hole he must enter. In the small cavern within, Link must jump from rock to rock across the lava, and defeat the two NaN Magtails at the end of the cavern to reveal this island's treasure, the Power Bracelets. This will allow Link to lift giant rocks he normally couldn't, allowing access to the Earth Temple and the Savage Labyrinth. The timer will stop, and using the Power Bracelets, Link must lift the large stone boulder in order to exit.

In the surrounding waters, a Big Octo lurks, rewarding 100 Rupees upon its defeat.

Trivia

 * A beta version of the main island, called "kazan", is present in the game's files and can be accessed using the map select or exit modifier codes. Differences from the final version include very early textures on the water and rocks (a static purple color for the water and a simple checkerboard for the rocks) and a larger entrance at the top.
 * The inside of the mountain also has a beta version present. It is much larger than the final version; it consists of a room containing the main warp in and out, then a hallway, followed by the main room, where Link must jump across lava on platforms while dodging Fire Keese. The treasure chest at the end of the room contains the Power Bracelets, but another room, similar to the first, is behind it; it contains nothing. The room also uses early textures, like the outside, though not as primitive.
 * In Tingle's comment on Fire Island, he possibly references the Goron Tunic, which allows Link to safely traverse hot areas in Ocarina of Time.