Go to the Kakariko Village. Enter the Skulltula House if you've gotten 10+ tokens. Find the boy and he will give you an ADULT WALLET. Now you can hold up to 200 rupees! Now go to the Goron City.

Go to the second floor and look for a rolling Goron. Stop him with a timed bomb. Then he will talk to you about the Gorons and Volvagia. He gives you the GORON'S TUNIC, a flame resistant suit! Now you can walk on lava! Go down to Darunia's room and pull the statue to.... reveal a secret passage! *gasp* Enter the passage and you're in the middle of the Death Mountain Crater! Equip your Goron Tunic to prevent the heat. Go left and hookshot the log above the bridge. Then you'll meet Sheik yet again and learn the BOLERO OF FIRE. After that, go left and down the hole to enter the Fire Temple.

Go left and enter the door. Kill the Like-Like. If you got sucked by the Like-Like, you will lose your tunic AND shield. Kill it to get the tunic back. Open the chest to get the shield back (if you lost it). If you killed the Like-Like without losing anything, kudos to you. Open the chest (if didn't get sucked) to get.... a GREEN RUPEE! Gah.

Go back out and jump on the shoulder of the stairs to avoid the fire at the base of the stairs. Then use the Din's Fire (if you don't have it, go back to the Hyrule Castle section, second section above here) to light up all of the torches here. Enter the opened door.

Whooo! You found Darunia! Wait... he says that he has to leave to seal the dragon (Volvagia) and asks you to save the prisoners... Oh well. When Darunia leaves, go right and jump on the platforms then use the hookshot to attach yourself to the target. Then climb up the steps and break the crates. Then stand by the target and do the Din's Fire magic to light up both torches. Quickly jump off the platform westward, toward the other side of the room. Get up on the platform with an unlit torch. Use the Din's Fire to light up that torch before the other two torches go out. If you're fast enough, the gate to an alcove will open. In that alcove is a chest with a SMALL KEY. Leave the room.
~TiteHotmail adds: "Instead of running across and using the Din's Fire again you could just use Din fire in top of where the crates are and use it (lightin up both torches) and then use the bow and arrow to light up the torch on the opposite side." In other words, you can fire an arrow through the fire to the other side. I never thought of that. Go down the stairs and use the small key to unlock the door with a lock. Kill all of the enemies here (be careful, the skeletons can inflict large amounts of damage!) to open the door. Use your shield to block the floor's attacks (there are 5). And break open the jars in the south corners for fairies. You can capture them if you want. Then wake up the armored solider sitting on the throne (attack him to wake him up). L-target him and get close to lure him into attacking. Before he attacks, get out of the range. When he's done with his attack, get in close again and strike him. After about 8 strikes, his armor will go off. Just go up to him and attack like crazy until he dies. The locked door will finally open.

In the next room, you will fight a mini-boss. The boss has three forms but they all attack the same and you use the same method to beat all three forms anyway. To kill the mini-boss, use your hookshot to get the boss out of the fire body. Then use the arrows or your sword to damage him even further. Repeat with the other forms (fire, ice, and forest). When you kill him, the chest will come out in the middle of the room. Take out the prize. The prize? The MEGATON HAMMER! Cool!

Leave the room and use the Megaton Hammer to press the rusted switch down. Then open the chest (DUNGEON MAP) and talk to the Goron. He will thank you and leave. 1 down... Leave the room via the far door. You're back in the original room. Climb the shoulder and up the stairs. Go right... see that weird looking statue? Get rid of that statue by using your Megaton Hammer. Then enter the door behind it.

In the large lava room, go left (use the platforms) to the door. In that room, there is a rusted switch. Smash the switch in with your Hammer. Then talk to the Goron. Don't forget the Golden Skulltula behind the Goron.

Back in the big lava room... go all of the way across the room to the wall of fire. Get on the moving platform (next to the wall of fire) and hookshot to the torch to pull yourself over the fire. Then bomb the colored wall and enter the door. Use the Din's Fire to light up the torches in the room and talk to the Goron. Open the chest for a SMALL KEY. Go back to the big room. Again, go back to the other side. There is a platform that will rise when stepped on. It's in the northeast corner. Use the platform to jump to an alcove in the wall. Use the Din's Fire to light up that fire and shoot an arrow through the fire to another torch (near the door). Drop to the lava below and climb the platform to the right. Use the hookshot and the target to get to the door you just unlocked by shooting a fire arrow.

In the new room, have your shield ready for the attacking floor boards. There are 8 so wait until all 8 have broken. Then use the torch to hookshot yourself to the other side of the firewall. Open the chest for the BOSS KEY. Use the torch in the middle of the room to get back. Return to the big room. Use the small key on the locked door. Climb up the screen (bars, whatever you want to call it) to the top and jump to the platform with fire on the bottom. The platform will go up to 2F. Walk off the platform and enter the door.

Look around the room a bit... then go left and up the platforms. Use the Din's Fire to light up the torch. It will trigger an event where a target will come up. Jump to the platform where the target is on. Jump on the top of the target and jump off it ot the higher platform. Kill the Lizaflos and climb up to 3F.

I was stuck in this 3F for so long that I nearly gave up... Man... You're lucky that you have my guide to get through this part. Go to the south part of the room and do a spin attack through the bars to trigger a switch. Then break the crates to uncover a chest with BOMBS. Go to the other side and bomb the wall (well... hard to explain WHERE... it's just in the south part. There's two walls that can be bombed. They're next to each other, only a barrier divides them.) Smash the rusted switch. then use one of the targets to pull yourself on the barriers. Look around for a cracked floor. Use a bomb to make a hole. Drop to 2F.

Break all of the crates to find a rusty switch. Smash the switch to open the gates. Open the chest to find a COMPASS. Go back up to 3F, use the fences to climb up. Go down to the lower floor of 3F. Make sure you've bombed the wall left of the switch you just used to bring out the targets. After that, go back up to the top part of 3F.

Then jump all of the way to the other side. Stand on the edge as close as you can. You should be facing a locked gate with some crates behind it. Do a FULL magic spin-attack to open the gate. Jump to the opened alcove. Smash the crates but not the little boxes. Open the chest for BOMBS. Then pick one of the boxes and run all of the way (avoid the Lizaflos!) to the part where I told you to bomb. Put the box on the switch and enter the door.

Finally, a Goron! Talk to him and he'll thank you and leave. Open the chest for a SMALL KEY. Go back to the previous room and get on the top part of the room. Use the small key on the door on the right. Ignore all of the boxes and crates and go to the other side. Do not enter the door, just go back a bit and get on a fenced platform that can be jumped to a higher solid platform with a crate and 2 little boxes. Do not break the crate, just grab a box and drop down and place the box on the switch. Use your hookshot on the crate to get back up. Now, you have to light up a fire near the ceiling... To do that, go to the lit torches and shoot an arrow through one of them to the other torch. A door will unlock. Go into the door.

Look right, you should be able to see the block of time. Get on it and jump off to the large platform. Stand on the middle (on the face) and smash the platform with your Hammer. The platform will go down all of the way to 1F. Now you can access the boss.
***NOTE: You must be wondering: what happened to 4F and 5F? You forgot about that part! Relax... No, I didn't. 4F and 5F are not mandatory to beat the dungeon. The only important things that are ahead: Gold Skulltulas. If you want to go and collect them, go ahead. I'm not covering that part because this is a Walkthrough not a Secrets FAQ. Also, it might be better if you beat the boss first because the platform in 1F will bring you up to 4F. So I guess it's better to beat the boss first. END NOTE***

First of all, fill your bottles with fairies. Then go to battle.
Volvagia will stick its head out of the ground. Quickly go to the head and smash it with the Hammer. The dragon will scream with agony and faint for a while. During that time, attack the dragon with your sword! When the dragon have taken some damage, it will fly over the platform, spouting fire. Just stay on the platform and fire arrows at it. After that, wait for the dragon's head to come up and strike it with a Hammer again and strike it with the sword. Finally, the dragon will fly wayyyy high and make the boulders fall to the platform. Just stand there and press R (shield) and block upwards. You are unlikely to get hit if you do this. Continue fighting. Have your Hammer out when the head's coming out of the platform so you are ready to strike it quick. It won't take long before the dragon dies.

Take the Heart and say bye-bye to the Fire Temple. The warp will return you to the Chamber of Sages. Guess who's the Sage of Fire? Yes, Darunia. He will give you the third medallion, the FIRE MEDALLION.

Now that you have the Hammer, you can break very hard boulders (red rocks) now! Get across the hole in the bridge by using the Hookshot. Then go to the place with two boulders blocking a path. Break them both with the hammer and enter. You've entered a Fairy Fountain! Sing the Zelda's Lullaby on the Triforce and your Magic Power will double! Now go back out and go right (break the boulder on the way) and jump onto the next platform and climb the ladder. Walk to the edge. You won't fall over, you just will climb down the rocky wall. Climb down until you reach an alcove with a Piece of Heart. Now time to look for the Water Temple.