This walkthrough is meant to get you through the level, not get you all the secrets. I will only cover what is required to get through the level.
Right when you enter the fire temple, go up the stairs and take a left. In here you will see Darunia. Talk to him and he'll tell you whats going on. Once hes gone, follow the columns on the left to get to the door over there. Inside will be a trapped Goron. Free him and talk to him. Once hes gone, take the chest in there and leave. Use the key on the room that had the lock on it. This door leads to a room that has a huge bridge in it. To get to each side, simply jump from column to column. On the left part of the room there is a stone of time. Play the song of time and the way will be free to go into and free the Goron. As before, take the treasure and go to the other side of the room. To get inside, blow up the door and walk on in. As of before, free the Goron and get the key. Now that you have two keys, go back to the bridge and unlock the door.
The next room has a huge path of fire shooting up into the ceiling. To get up where you need to go, climb the linked fence in there. Once up, jump to a smaller ledge below you and push the block down where the fire is coming from. Now that the block is on the fire, jump on it and you will be propelled up into the next room. Go through the door and proceed on. When you enter the next room, go left and climb the high balcony. Once your all the way up, jump across to where the block and switch is. Push the block down and use it to climb up the linked fence. Once your at the top, you'll see fire in the way of where you need to go. To get rid of it, throw a bomb down where the switch is. Once its out, quickly climb up.
Be careful in this next room, its a huge maze with huge boulders rolling around. Wander throughout the maze until you find 2 Goron prisoners in it. Once youve gotten them, look for a door in a huge building in the maze. This door will lead you up on a thin path far above the room that has the bride in it. Just make sure not to fall or itll be a LONG fall. Go through the door across from you and it will lead to a room engulfed in lava. Above the lava will be links you can walk on. Go on them and follow them till you reach a door (Not the one on the high ledge yet). This door is on the other side of the room. If you went through the right door, it will lead you on the upper part of the maze. When you get there, you'll see a crack on the floor of one of the columns. Blow it up and follow the long way down to free one of the Gorons. Climb back up and jump from column to column to a switch that opens a Goron cage. Look for him at the same level as you. Jump to him, free him and get the key. Now that you have a key, go back to the room that has the links on the floor. Now you can jump to the ledge. This ledge might seem un-jumpable, but you can jump to it.
The door will lead you to a huge fire maze. Go through it till you reach a door. Go through the door. You will pass through a hallway with a Goron. You cant do anything for him right now, so go on. The hallway will lead you to another room with a fire maze in it. Go through it until you encounter a switch. Hit it and the huge wall of flames will be gone for a few seconds. Jump up quickly and blow up the fake door and go through the real door. This door will lead you to a mini-boss. Take him out with your bombs and once he's dead, climb the platform and it will lead you up. In the next room, youll encounter something of what you encountered with the switch and the fire. Simply do what you did before and climb up.
The door will lead to the room with the Megaton Hammer in it. Climb all the way up and get it in the chest. Make sure not to fall or it will be a long, long fall. Once you have the hammer, use it to smash a little thing in the ground where you first started. It will reveal a hole that you go down into. Jump down and go to the next room. Use the hammer to hit in the little thing sticking up. Once done, use one of the boxes to put on the blue switch below. Once done, the door will lead to a block. Hit the block with the megaton hammer and jump down. It will bring you to a caged place. Use the hammer once again to hit the block in there. With this block down, jump down and you will be brought to the door where Darunia is. Now that you can reach the boss door, you can go to the boss…but what about the key? Simple, go the very beginning and go to the right where the statue is. Use the hammer to hit the pieces out of the way to reveal a door. Use Dins fire in the next room to light the torch that opens the door. From there, go on through to the next room that has another mini-boss. Once you kill him, go onto the door that was barred. Inside will be a switch that opens the Goron cage that has the boss key next to him. Now your all set.
Now that I spoiled all the secrets of this level, ill leave it up to you to defeat the boss…Good Luck.
Walkthrough by: Louis Nassetta