Goron Mines

Goron Mines is the second dungeon of Twilight Princess.

Entrance to the Mines
Link enters the mines through a passage in Death Mountain, which he can access after defeating Gor Coron in a sumo match. His objective is to find one of the three Fused Shadows here.

Themes and Navigation
The inside of the mines is filled with lava and flame geysers; to avoid them, Link has to use his Iron Boots to stick to magnetized platforms.

Link must seek out the three remaining Goron Elders, Gor Amoto, Gor Ebizo, and Gor Liggs, in order to piece together a key to get into the boss's lair. The dungeon has two floors and contains many large rooms, some with walkways over massive pools of lava. The mini-boss guarding the Hero's Bow is a Goron Guardian. The dungeon's main boss is the Goron Patriarch Darbus, who was transformed into the Twilit Igniter Fyrus.

Frequently-encountered enemies include Torch Slugs, Dodongo, and Beamos. Link will also encounter several Bulblins, which wield bows or clubs. Some rooms of the dungeon are filled with water, which (contrary to popular belief) is not strange even for a fire-themed stage, since any mine is usually expanded to the point of discovering subterranean fountains of water.

The Goron Mines also are notable for featuring what's possibly a Hylian advancement in terms of technology, mainly thanks to the complex machines that operate to keep the place functional, including magnetic cranes, elevators and minecarts; Link can take advantage of the machinery available to explore the dungeon. However, whether these mines previously used to be Dodongo's Cavern or the Fire Temple, both from Ocarina of Time, is a mystery. Like Dodongo's Cavern, it's a long and extensive cave with areas full of lava, it has two floors, and it's populated by Dodongo. Additionally, Link does not need to worry about the temperature, despite the hot environment.

On similarities with the Fire Temple, it is located inside the Death Mountain, it's populated by Gorons and some rooms have tall fences made of metal bars. There is also a secret-wise reference to the aforementioned Fire Temple. Within Ocarina of Time's Fire Temple, there is a certain room which can only be reached by returning to the Fire Temple and using the Scarecrow's Song. Although it is not required to actually get to the room, the Longshot is required to obtain the treasure within. In the Goron Mines, the room with water at the bottom which contains multiple Bulblin archers also contains a Treasure Chest which can only be reached after retrieving the Clawshot from the Lakebed Temple. However, instead of containing something very rare like a silver rupee, it contains a mere purple rupee.

Theory
It is possible that the Goron Mines are actually an expanded Dodongo's Cavern. Both locations are mines deep within Death Mountain that are very important to the Gorons, and both are also inhabited by Dodongo. As the years went by and veins of desired rock required ever greater effort to retrieve, the Gorons would have expanded Dodongo's Cavern and perhaps built structures to make mining easier, accounting for the rooms and machinery throughout the mines in Twilight Princess.

Trivia

 * The dungeon's music may contain an extract of the Goron Lullaby from in the background.
 * This is the only dungeon in the game whose main treasure item is not obtained in the same room where the sub-boss is found. The Hero's Bow is collected one room after the battle arena where Dangoro fights Link.
 * The Hero's Bow is theorized by some to be the Hero's Bow from Majora's Mask. Upon returning from his quest in Termina, Link would have brought the Bow he found in the Woodfall Temple to Hyrule.
 * There is a hidden area along the cliff wall just to the north of the Bridge of Eldin that brings Link into a cavern that looks like a part of the Goron Mines.
 * If the "Early Master Sword" glitch is performed, this dungeon becomes inaccessible due to the Gorons blocking the entrance. They move to the sides, but Link is still unable to pass through. The game thus cannot be beaten without performing an elaborate series of actions to access the Mines with the Spinner.
 * Goron Mines is the only dungeon in the entire Legend of Zelda series in which neither the mini-boss or the boss (Dangoro and Fyrus, actually Darbus) are actually killed, both of them being good-natured Gorons and not actual enemies.