When you enter the temple, head forward and hop over the couple floating platforms. Once on the other side, there will be gears to the left and right side. Cut the ropes on them to lower the bridge partially and then send the Beetle out to cut the last rope through the hole on the right side of the drawbridge. Once it is down, head through and you will meet some new enemies called Lizafos. Once you defeat him, take his tail and then fire your sling shot at the bombs on the statue in the lava.
When it explodes, a ball will roll over. Hop on top of it and roll to the right of the area. When you hop off, talk to Ledd there and he will tell you about his Bomb Bag. Crawl through the opening to the left of the destructible rocks and then take out the enemy. Roll a bomb through the same opening to open the door and head through. Take out the two Lizafos inside and the bomb bag will appear in a chest. Hop back on the ball and roll over to the center of the room and head up the stairs on the left side. Toss a bomb at the rock pile and then hop across and go through the door.
Fight off the Red Bokoblins there and continue along the stones to the rising one at the far end. Ride it up to the chest a get the Dungeon Map. Head back out to the main room and roll over to the right side of the room. Look on the map to where the red X is and toss two bombs against the wall there to break it open. Roll through and when you come to the blocking bridge, toss a couple more against the wall on the left. Roll through the new opening and continue til you reach a red door.
Use the Beetle to cut the rope at the top and then send it through the tunnel on the left side to cut the second rope on the other side of the door at the top. Roll through the now open gate and follow the path to the main room. Roll against the plunger on the central bridge and it will rise up allowing you to enter the center door.
Once in, run up the slope in the center using the room on the left to rest. Avoid the rocks on the way to the top and then you will have another slope to climb. Use the opening on the right to crawl through and then dig to find the air spout allowing you to climb the stairs to the balcony there. Toss a bomb off so that it blows up the destructible rocks on the far side to the left and then head back down through the opening and run up the slope. Once at the top, go up the winding path to the left, grabbing the fruit along the way so you don’t slide back down. Once at the top, open the chest to get the Dragon Sculpture key for the door at the bottom. Once opened, a scene will play and you will have to fight against Scaldera, a giant rock and lava spider.
To defeat it, you will basically just need to throw bombs into its mouth and then slash at its eye when it explodes. Scaldera will repeatedly run up the ramp to the top and then roll back down where it will inhale and then shoot fireballs out. When it is inhaling is when you need to toss the bomb at it. Once it goes off, some of its shell will fall off giving you the eye to hit. Keep repeating and eventually the beast will wither away.