After retrieving the Water Dragon's Basin and helping Scrapper reach t he frog statue, you can enter the Fire Sanctuary.
Get a Key
Use the beetle to cut down the green plant (water fruit) that is hanging over the lava in your way. Jump over the lava platform before it crumbles.
Cut down the water fruit to the left that is hanging near the lava spout. Ride on the lava platform, using your bow to kill the bokoblins, and jump off at the end. Kill the blue bokoblin up ahead to get rid of the bars and reach the blue chest, which contains a key.
Get a Second Key
Drop down below. An old Mogma named Guld will appear. He will mention the ancient treasure of this temple. The legend says "Ye who seek the entrance to the king's treasure, look for the two statues that face one another. Show your bravery and jump into the mouth of the sleeping statue. Do this, and the path will open before you."
Go through the locked door and watch the cut scene, which shows you the boss door.
Follow the straightforward path. Some dark keese will pop out and attack. Go up ahead and kill the two bokoblins. Go through the door.
Go to the left to get 20 rupees, then go the other way. Jump down into the lava area. A magmanos will pop up. Stand on the brown platform and the magmanos will lift you up to the ledge.
Climb the vines to the right, kill the two bokoblins, then climb to the right on the vines. Kill the bokoblin there. Hop down and save at the bird statue. Go through the door.
A dark lizalfos will attack. Avoid its cursed breath, which will stop you from using items for a while. If it knocks you back with its arm guard, quickly do a shield bash to avoid its counterattack.
After you kill it, go through the door. Bomb the cursed spumes, kill the two bokoblins at the far side of the room, and kill the dark keese that fly down.
Send the beetle through the passage with the rupees on it near the magma spout. At the end, there are a few bombs. Pick one up and fly to the magma spout that is partly blocked with rocks. Then use the beetle to knock down a water fruit, and ride it to the far side of the room. Go through the non-locked door.
A mogma is trapped above the lava. Use the gust bellows to get rid of the magma chunks in the way. Open the blue chest to get a key.
Get the Mogma Mitts
Go to the previous room and go through the locked door. Cut the water fruits in your way. Open the chest around the corner to get 20 rupees.
Go up the stairs to get an evil crystal from the blue chest. Stand on the platform across from the frog, then do a sword thrust on the water fruit on the other side. The fruit will get stuck on your sword and you can swing it at the frog statue to open the way.
Kill the bokoblins and dark keese up ahead. Save, then go through the door.
Go down to the bottom, then get onto one of the brown platforms and let the magmanos raise you up. Get a water fruit on your sword with a thrust. THen go back down to the bottom and run around to make a magmanos come up. Hit the magmanos with the water fruit to make it solidify, then repeatedly hit the magmanos to make it crumble. Repeat with the second one.
After the lava disappears, go through the door. Go to the bottom and run up the wall to pull the red bar and free the mogma. He will give you the Mogma Mitts. You can use them to burrow into special holes in the ground.
Get the Map
Go over to the holes near where you got the mitts. You can burrow into one of these holes. Flick the Wii Remote to attack things in your path. Do this to break the rocks in the way. Press Z to see above ground. Attack the bomb to make it roll into the debris in your way, then go around to the light shining down. Press A there to go back above ground.
Use the gust bellows to blow the magma chunks away. Dig into the hole near the bars to burrow again. Go to the red side of the block and attack it to make the bars move out of the way. Go back to the light spot and emerge with A. Then go to where the bars were. Go through the door there.
Go to the right and kill the bokoblin. Step on the switch to remove the bars, giving yourself a shortcut. Go back to the door that you came in through and use the bow to kill the three bokoblins across the way.
Jump down to the lower level to find a goddess wall. Use the clawshot to go back up, but be careful of the bokoblin archer above the door that you came in through.
Go through the door across from the one that you came in through.
There is another trapped Mogma up ahead. He promises to tell you a secret about the room if you free him. Find the digging spot that you can burrow into. Go to the top of the area and flip the switch up there. Then flip the lower switch. If you do it the other way, you won't be able to reach the bottom one.
Go back to the surface and do a thrust attack at the water fruit. Go up the stairs and throw the fruit at the frog statue. Pull the red bar down in the small room that you are now able to reach.
The Mogma plans to run away without telling you the secret, but then he recognizes your Mogma Mitts. He will bring up a blue chest and will tell you that there is a hidden room nearby, and that there is a fake wall. The chest contains the dungeon map.
Get a Third Key
The fake wall that the mogma mentioned is right behind you. Just look at the map to see where the passage is to see where to bomb the wall. After bombing the wall, burrow into this area to find the hidden route. However, there is a caterpillar. To kill it, hit the orange thing on its back when it stops moving around. You can hold the A button to move more quickly, but this uses stamina. Each time you hit the caterpillar's orange backside, it will run around more quickly for a while. After you hit it a few times, it will die. Emerge at the other spot of light in this area.
Open the chest to receive a key.
Get an Empty Bottle
Go back to the last room using the vines. Exit the room through the door that you originally came in.
Go back across the broken bridge, then go through the shortcut near the opposite door where you stepped on the button to remove the bars. Don't go through the nearby door. Instead, go across the non-broken bridge and through the door on that end.
Go to the left and burrow in the dirt here. Hit the switch to move the bars, then emerge again. Go around and step on the switch, then use a water fruit to kill the magmanos down below. The lava will go away and you can access a room that leads to a blue chest, which contains an empty bottle.
Get a Piece of Heart
Go back to the door on the west end of the broken bridge and go through. You can now unlock the door near the bird statue.
Use the beetle to knock down the water fruit. Jump across. Bomb the cursed spume at the other end. Kill the red chuchus up the stairs and go through the door. Kill the bokoblins and dark keese. Go up the stairs, killing the cursed spume on the way. Burrow here. Switch the gate. The mogma will switch it back, so go talk to him, then chase after him. Hold the A button to move more quickly. Once you intercept the mogma, he will bring up a blue chest that contains a piece of heart.
Get the Mysterious Crystals
Bomb the cursed spumes and use the beetle to hit the water fruit. Ride the platform to the other side. Step on the switch to lower the bars, then save at the bird statue. Burrow into the hole behind the bird statue. Go to the bomb and knock it into the rocks, then hold the A button to hurry back to the exit. Don't let yourself run out of stamina. Let go of the button if you are close to running out, and use stamina fruit when possible. Emerge at the beam of light.
Go back down to the lower area by using the door past where you lowered the bars. Then you can knock down a water fruit and ride it to the far end. Up ahead, read the sign. Look down below and you will see the "sleeping statue" that the old mogma, Guld, talked about. Run off the edge to the left, where the statue with closed eyes is. A platform will appear below you as you get close. Use the sailcloth to avoid getting hurt. There is a goddess wall up ahead. Go through the door at the top of the stairs.
Kill the dark lizalfos. Go through the door up the stairs. There is another goddess wall here. Go up the stairs. Use the clawshot to get up over the gap. Use the A button to run over the other gaps. Open the door at the top.
There is a puzzle in here. Burrow into the hole and then step on the blue switches in the order of the number of wings on each statue. Press Z to see the statues while you burrow. Hit the bomb to make it break the rocks in your way. When you activate all of the statues in the right order, you will have to kill the caterpillar to escape. Once you do that, emerge from the hole and open the chest to get the Mysterious Crystals.
Reach the Dungeon Boss
Go through the door that you didn't come through. Step on the switch to remove the bars. Save at the bird statue and use the Mysterious Crystals on the locked door.
Ghirahim is here. In the first phase of battle, you can knock away the daggers by slashing in the appropriate direction. Then hit him from the direction where his hand isn't blocking.
Keep attacking him this way until he takes out two swords. When he makes daggers appear, slash in the appropriate direction to get rid of them. If they appear in a circle around you, swing the nunchuk and remote horizontally in the same direction to do a horizontal spin attack. If they appear in an arc above you, swing the nunchuk and remote vertically in the same direction to do a vertical spin attack. If he throws daggers, slash in the appropriate direction to knock them back at him.
If he leaps into the air, run around and wait for him to land and get his swords stuck, then run back and hit him if you have time.
When he holds the swords at an angle, hit in the vulnerable direction. If you do it incorrectly, quickly do a shield bash to avoid his attack.
Get Din's Flame
After defeating Ghirahim, get the heart container, then go through the glowing door. Hit the crest with a skyward strike.
After your sword is transformed, Fi says to go to the gate in the sealed grounds, so go back to the sky and fly to Faron Woods. Land at the Sealed Grounds statue.