Ice Cavern
Requirements: Empty Bottle/s, Song of Time, projectile weapon (preferred)
Hints:
BEFOREHAND
By the time you get this far in the game, you'll have at least one Bottle. It's easier if you have two or more empty Bottles, but one will do. It's also a good idea to have a projectile weapon like the Hookshot or Bow, but they're not necessary.
Travel along Zora's River to the Sleepless Waterfall. If you haven't planted the Magic Bean here in the past, then you'll have to use the warp at The Lost Woods. Go through the waterfall to Zora's Domain, which is frozen over. Go through the caves to Zora's Fountain, which though not completely frozen over does have several ice floes.
From where Lord Jabu-Jabu used to be, jump along the floes to the left and you'll come to a cave entrance on a high ledge that Young Link couldn't reach. You'll now be in the Ice Cavern.
BRRRRRRRRR!!
If you hear a scraping sound during this cavern, it means that stalagtites are threatening to fall from the roof. Raise the Shield high to avoid damage, but you can run straight through the passages to easily avoid them.
From the entrance go straight down the passages, cutting the stalagmites out of the way with the sword. You'll come to a room with ice monsters called Freezards; simply stay away from their face to avoid their ice breath and hack them repeatedly with the sword. When all are gone, go through the door to come to the ice blade room. Here, gather all of the Silver Rupees to open the door; jump from the ledge to get some, another is behind some stalagmites, and others you'll have to get close to the ice blade. Hold R to duck and avoid the ice blade.
After you get all of the Rupees, go through the opened passage. Here will be several Freezards and Ice Keese: knock them all out before doing anything! When they're all down, climb up the platforms to the Blue Fire Torch. Catch some flames in Bottles, then look for the chest encased in Red Ice. Use Blue Fire to melt the ice, then open the chest to get the Map. A pot in this room which is also encased in Red Ice has a high-value Rupee. Make sure all your Bottles are filled with Blue Fire before returning to the ice blade room.
Upon re-entering the ice blade room, go left to find some Red Ice in the wall. Melt it with Blue Fire and go along the passages to reach a room guarded by several bats and another Blue Torch. The chest in this room contains the Compass, and you must burn away the Red Ice in order to open the chest. Once you have the goodies, return to the ice blade room and go to the Red Ice set in the wall directly opposite from where you've just come from. Melt the ice and proceed along the passages.
You'll come to a room with a slippery floor and plenty of Ice Keese. Knock out the Keese and be careful of the edges of the room, which have bottomless pits. Near the entrance to this room is a large ice block: what now commences is one of the most frustrating points of the game.
You must push the ice block along the floor in order to reach the higher platforms with the Silver Rupees. You can't pull the block, but you can push it into the bottomless pits to have another block rise at its original location. One Rupee is to the north of the entrance, encased in Red Ice. There is a Blue Torch you can reach in the far west of this room: jump to the high platform near the Torch, then play the Song of Time to form stepping stones (and reach some Rupees).
Once you have all of the Silver Rupees, the south portcullis will open. Make sure you have a Bottle of Blue Fire for the final Red Ice barrier. Proceed along the passages for the final door, where you'll have to fight a White Wolfos. Defeat him as you would a normal Wolfos: lock onto him, then wait until he comes towards you and raises his paw. Strike Wolfie before he strikes you, then repeat.
When Wolfie is down, the chest containing the Iron Boots will appear. After you get the Boots, Sheik will appear and explain to you the fate of the Zoras. He will then teach you the Serenade of Water, so that you can quickly reach Lake Hylia. Once you have all of the necessary gear, look behind the chest containing the Iron Boots for a pool of water; don the Boots and sink down for a door, which leads to the first room.
From the first room you can easily reach the entrance, but remember to have at least one Bottle of Blue Fire so you can thaw out King Zora back at Zora's Domain.