- "This ice is created by an evil curse... The monster in the Water Temple is the source of the curse. Unless you shut off the source, this ice will never melt...."
- — Sheik
The Ice Cavern is a mini-dungeon from The Legend of Zelda: Ocarina of Time. This cavern is located in Zora's Fountain and acts as a prerequisite to the Water Temple, though it can be completed as early as prior to the Forest Temple.
Link finds Zora's Domain frozen, with the Zora encased in thick ice, and Lord Jabu-Jabu nowhere to be seen. When he returns to Zora's Fountain, a series of Ice Blocks which he must traverse have appeared, leading to the previously inaccessible Ice Cavern. Within the cavern, Link finds Blue Fire, an unnatural substance indigenous to the cavern, which Link can put into bottles and carry around with him in order to melt the Red Ice found throughout the cavern.
After navigating the dungeon, Link is confronted by a White Wolfos; after its defeat, a Treasure Chest appears, which contains the Iron Boots. Suddenly, Sheik appears and informs him of the fate that befell the Zora people. Once Ganondorf used the Triforce of Power to wreak havoc on Hyrule, he conjured up the being Morpha, effectively cursing Zora's Domain. Almost all of the Zora were sealed under the ice, but Sheik managed to rescue Princess Ruto from this fate. Ruto afterwards headed to the Water Temple within the depths of Lake Hylia. Sheik teaches Link the "Serenade of Water" inside the cavern, the warp song leading to the Water Temple.
The Ice Cavern only has one floor. There are a few rooms that are connected by hallways, which are blocked by red ice walls. Most rooms have Blue Fire. The main puzzles in this dungeon are the collection of Silver Rupees, which open barred doors. Sliding Ice Blocks are introduced in the North-center room and return in the "Water" section of Ganon's Castle. The North-west corner room is where Link obtains the Iron Boots, which must be put to use to exit said room. The Southernmost room is optional, but it contains a Gold Skulltula, a Piece of Heart, and the Compass.
In the Master Quest re-releases, several changes have been made to the dungeon, including puzzles and the order in which the rooms are visited. Overall, the dungeon is much shorter and features many puzzles that need only be completed in order to get Gold Skulltula Tokens, such as the room containing a puzzle involving Ice Blocks. It also features new enemies such as Boulders, Tektites and Wolfos. Two White Wolfos are found in the central room of the dungeon and instead of a White Wolfos, a Stalfos guards the Iron Boots.
Snowpeak Ice Cavern
Given its general location, freezing climate, and proximity to Zora's Domain it is possible that the Ice Cavern is part of the Snowpeak mountain region from Twilight Princess. While Snowpeak does not actually appear in Ocarina of Time it is possible that mountain existed and was simply inaccessible during the events of Ocarina of Time, save for Ice Cavern, which Link was only able to access due to Ganondorf freezing Zora's Domain and Zora's Fountain. One possibility is that over time the cavern turned into the cave that connects Snowpeak to Zora's Domain (albeit reduced in size), thus creating way for people to access the mountain region of Snowpeak.
It should also be noted that if the Ice Cavern was a part of Snowpeak then that may explain the presence of White Wolfos and Ice Keese (which are relatively common to the Snowpeak region) in the cavern, although this may simply be due to the fact these monsters prefer cold climates.