Magical Warp Tile

The Magical Warp Tiles, or simply Warp Tiles (and also known as Magical Transporters) are mysterious portals that transport anyone brave or foolish enough to stumble into them to the evil Dark World. There are eight of them in all. Due to the efforts of Agahnim in sending the Maidens to the Dark World, he also manages to open a similar portal to the Dark World at the gateway to Hyrule Castle.

Location and Function
Most are hidden underneath rocks, but the one at the peak of Death Mountain is open and easily to stumble into. Those who walk through these portals are transformed into a shape that reflects their heart by the power of the Triforce. This is usually that of a monster or animal. Not only this, but these warps are one-way; there is no way for normal people to return from the Dark World due to the seal of the Seven Sages. Only Link is able to return, using the Magic Mirror. By using the Magic Mirror, Link will leave behind a sparkling gate at his return location that will allow him to transport back to the Dark World.

The eight Warp Tiles are found across Hyrule:
 * On Death Mountain next to Spectacle Rock, south of the Tower of Hera
 * Near a Fairy Fountain due south of the Eastern Palace (Magic Hammer and Power Gloves required)
 * In the northwest corner of the Great Swamp (Magic Hammer and Power Gloves required)
 * North of Kakariko Village, on the verge of the Lost Woods (Magic Hammer and Power Gloves required)
 * On the island containing the Pond of Happiness at Lake Hylia (Titan's Mitt required)
 * On a small outcrop in the southwest corner of the Desert of Mystery (Flute and Titan's Mitt required)
 * On the lower eastern side of Death Mountain, near the broken bridge (Magic Hammer and Titan's Mitt required)
 * At the far east side of Death Mountain, on top of the rock that mirrors Turtle Rock in the Dark World (Magic Hammer and Titan's Mitt required)

To retain his normal form after passing through a Warp Tile, Link will have to obtain the Moon Pearl.

Trivia

 * The Magical Warp Tiles represent the first time Link is able to warp from one world to another in the series. The Warp Tiles have gone on to directly inspire other such methods of warping, such as the Moon Gates in Four Swords Adventures, the portals to Subrosia in Oracle of Seasons, and even the Pedestal of Time in Ocarina of Time, among others.