Deep in the Eldin Canyon Depths, you find the Fire Temple of lost Gorondia.
Enter the Temple
After the cutscenes, talk to Yunobo, then go the rocks that are blocking the temple entrance. Have Yunobo break them down. Go farther ahead and talk to Yunobo, and there will be a cutscene.
Create a Teleport
Nearby, you will find the glowing object that allows you to create a teleport back to here, so check on it. After you do, the locations to unlock the padlocks on the gate will be added to your map.
Unlock a Padlock
Go east, then go south when you can. Defeat the Construct, then go east. You find some platforms moving through the lava. The platforms are created by a Zonai Hydrant that is pouring water onto the lava. Jump across using one of the moving platforms, then pick up one of the inactive Hydrants and set it on the floor. Hit it to activate it, then pick it up. Walk toward the lava and let the Hydrant pour water on it. Wait for a platform to form, walk onto it, then use the Hydrant to make more platforms appear. Keep doing this until you have reached the other side. Set down the Hydrant and hit it to turn it off.
You reach some mine carts, and a strange device in the corner. If you hit the device, you will see that it makes a section of the floor rotate. Keep that in mind for later.
Get in the cart on the rail and hit it to start the fan. You will see a rock blocking one section of the rail up ahead. Wait until the cart is starting to turn right, then have Yunobo destroy the rock. The rail will send you in a circle, back to where you started, so on your next trip around, hit the device straight ahead to change the tracks. You will reach the end of the rail, so hit the cart or the fan and get out.
Go south and defeat the Fire Like. You can wait for Yunobo to stun it, then hit it while it is stunned.
Go north and take a Hydrant, and use it to make solid platforms in the lava. Use Ultrahand to attach these platforms and make a bridge across the lava. This will allow you to have Yunobo break the rock up ahead without falling into the lava.
Go through the door where you broke the rock, and have Yunobo hit the Gong.
Unlock a Second Padlock
To the left of the exit of the gong room, there are some Hydrants and Hydrant Capsules, so take the capsules, and use the Hydrant if you need more platforms to be able to cross the lava.
Go back to where you got out of the mine cart, then hit the glowing crystal next to the rail. This will remove the barrier. If there is no cart on the rail, pick up one of the nearby ones and place it so that it is pointing west. Get in and hit the cart or the fan. Break the rock on the rail if there is one. You will be attacked by Constructs on the rail nearby. If you can manage to stop your cart in this area, you can defeat the two Constructs in the carts, then get into one cart, turn the other around, and ride it around the loop to reach a treasure chest to the south that contains a Diamond.
Back on the middle rail, go north, and watch for the treasure chest to the right of the rail. Be aware that it will be difficult to get back to this spot if you fall.
At the end of the rail, turn the cart around, get in and hit the cart or the fan, then have Yunobo hit the device up ahead to switch the rail. When you reach a barricade, get out and defeat the two Igneo Pebblits, then hit the rotating device to rotate the rail up ahead. This will also open the barricade, so get in the cart and go to where you rotated the rail.
Get out when the cart stops, defeat the Construct, then open the chest in this room.
Ride a cart back along the rail until you are back at the device that you used to rotate the rail. Cross the short bridge here and hit this other rotating device, which will lower a rail and open the barricade nearby. Put the cart on the track and ride it to the end.
Have Yunobo break the rock in the lava, then wait for a platform to go underneath the see-through floor and use Recall on it. This will push the oncoming platforms in front of you, allowing you to reach the far side of the room.
Defeat the Construct here, then have Yunobo hit the gong.
Unlock a Third Padlock
Before you go, you can use Ascend to reach a ledge on the west side of the room, where you can get a Fan Capsule and Hydrant Capsule, and you can jump across to the east side to reach a chest that contains three Zonaite.
Then glide south, or if you went straight down, you can jump onto a platform that the hydrant creates, and it will take you back to the south side of the room.
Rotate the cart in the rail on the left and hit the cart or the fan, but then when Yunobo appears at the front of the cart, hit the cart or the fan again to slow down the cart, and have Yunobo hit the switch to the left of the rail, then hit the cart or the fan again. This will raise the rail up to the third floor. (If the cart gets stuck, just turn off the fan and let it go backward, then place it on the rail again and get back in and go. There is also a backup cart in the area that you started from.)
On the third floor, go south and defeat the Construct. Get the Rocket and Hydrant Capsules from the area near where the Construct was, then open the chest that is to the right of where the capsules were. Be sure to hit the glowing switch to make an elevator that goes down to the second floor; this shortcut will be helpful later.
If you hit the two switches on the north side of this room, you will see that you can rotate the rail, as well as raise and lower it. For now, raise the rail, then rotate it so that it is going north from this area and will take you up to 4F. Get in a cart to go up that rail to 4F.
A Construct will be in a cart beside you. Have Yunobo hit it. The rail here goes in a loop, as you can see on the map. When you are on the south side of the loop, get out of the cart where there is a ramp near the southeast part of the loop.
Go north into this room and send Yunobo up the short ramp to hit the glowing rock there. This reveals a hydrant up above. Take the platform that it creates, and attach it to the long platform that Yunobo used as a ramp. Attach two or three more platforms to the end, then place this long platform somewhere that will allow Yunobo to use it as a long ramp to hit the gong up above.
Unlock a Fourth Padlock
Before you go, you can detach the end piece of the ramp that you created, then reattach it at an angle pointing up. Take it to the end of the broken bridge that points southwest, and place it on the ground for Yunobo to roll on. He can break the glowing rock on the other side by using this ramp.
Now go to the platform at the southeast part of the rail loop in this area, and glide southeast to 3F from here. Use a cart to go west, then have Yunobo break the glowing rock, if any. This reveals a rotating device. If the barricade is blocking the rail, hit the rotating device to raise the barricade, then use a cart to go southeast.
Go to the two switches that are side by side, and use them to make the rail go east-west without being raised. Get back in a cart to go northwest to where you just were, and the cart will take you to where there is a treasure chest that contains a Strong Zonaite Shield. Ride the cart back the way you came.
Now go to those two side-by-side switches and raise the rail so that it is going east-west, with the east side raised. Then get back in the cart that goes northwest, and let it take you up to 4F.
In the room where you stop, defeat the Construct, then open the chest. Then get in the cart on the other rail that goes north (the one at the northwest corner of this platform) and hit the cart or the fan. There will be a Construct in a cart coming toward you, so have Yunobo hit it, then get out at the top and defeat the Construct if it's still there.
Go to middle of the northeast edge of this platform. If you already broke the glowing rock beneath where you are standing, skip to the next paragraph. Otherwise, go counterclockwise around this platform, and be careful of the broken piece of the bridge on the northwest side of this platform. At the end of the bridge, glide down to the platform below you. Go northeast and hit the device to lower the rail, which opens the barrier here. Get in the cart and ride to the other end. Then turn the cart around and go back up, and have Yunobo break the glowing rock that is in the wall to the left of the rail. Then use Ascend to go back up to the platform above you.
From the northeast edge of this platform, glide down to where you broke the glowing rock. Go southwest to where there is a hole in the floor. Glide down to 4F, then down to 3F, where there is a treasure chest near the northeast wall. Then glide down through the hole to reach 1F, where you find a treasure chest in one corner, and a gong. Have Yunobo hit the gong.
Unlock a Fifth Padlock
Hit the switch next to the gate to open it. Go southeast, then go east from the large gate with the padlocks. If you hit the switch to start the elevator earlier, there will be an elevator going up and down, near the eastern door of the temple. Stand on it to go up to 3F. (If you didn't activate the elevator earlier, you'll have to ride the rails to reach 3F. Be sure to activate the elevator when you get there.)
Go to the south wall and take a Rocket from one of the niches in the wall. Attach it to the back of a mine cart, then put the cart on the broken rail that goes southwest. The rocket will give you enough momentum to get past the broken part. There is a risk that you will fall off of the cart since it's moving so quickly. If this happens, just glide back to 1F and take the elevator back up here.
Once you make it across, defeat the Construct. Go southwest to find a broken bridge, and another broken bridge in the distance. Go to the second broken bridge and attach the broken ends together, then go through the gap in the southwest wall to find a treasure chest beneath a couple of metal plates. Connect the two plates together end-to-end, then open the chest. After that, take the two metal plates to the first broken bridge and attach it to the side of the bridge that leads up to the glowing rock. This won't reach to the other side of the bridge, but it should create enough of a ramp that you can get Yunobo to hit the glowing rock on the other side. This will make some device capsules pop out, including a balloon capsule.
Go to the switch at the northeast edge and hit it to lower the ramp, giving you a shortcut back to 3F if needed.
To get an optional treasure chest, find the two carts that are hooked together, and use Ultrahand to pull them apart. Detach the hook then attach the hook to the inside of the cart. Hang this cart from the raised rail on the right (the non-broken rail) so that you will be able to jump into it from the ledge, but before you get in, attach a fan to the back of this cart. Then get into the cart (you can use Ascend to do so) and hit the cart or the fan. It will take you up to the next area. Open the treasure chest, then go back down the rail in the hook cart.
Use the Balloon capsule that you got from having Yunobo break the glowing rock at the side of the room, and attach the balloon to the top of one of the metal plates. Use a Flame Emitter (available from 3F if you didn't get a capsule) and attach it to the inside of the basket of the balloon. Place the metal plate near the northeastern of the two broken bridges so that when it floats up, you won't hit the ceiling. Get on the metal plate and hit the flame emitter or the balloon or the metal plate to float up. When you have reached 5F, glide out and land there. First have Yunobo break the glowing rock in the floor, then hit the gong.
Go Through the Gate
Now you can teleport back to the entrance and check on the glowing object to the right of the gate to open it. Go through the gate, then go to a wall where there is a large grey stone. Launch Yunobo up the wall here and he will be able to roll to the rocks in the ceiling and break them. Then you must battle Marbled Gohma.