Upon arriving, use the nearby Bird Statue and be sure you have the Iron Shield equipped; the Wooden Shield will burn to ashes here. Go along the path nearby. You’ll soon come to a Red Chuchu. Defeat it and head along the western path to find a Goddess Cube. Hit it with a Skyward Strike and go back to the fork in the path and along the eastern path. There, further along, you’ll meet a few Mogmas that tell you that, in no certain terms, that they saw a figure go by earlier, which is likely to be Zelda.
Continue along the winding path and, eventually, you’ll need to defeat some Fire Keese. Do so, then wait for the lava nearby to lower. Get on the left path to find some Bomb Flowers and a Mogma in a room. Practice rolling and throwing the Bomb Flowers, most notably into the rock piles to remove these obstacles. One on the ground has a giant Red Chuchu behind it; another yields a room in which you can sit to restore your health; and the last one is on a higher ledge.
Afterwards, continue going with the main path and you’ll eventually reach the outer area. Examine the nearby Bird Statue and drop to the lower-left area. Grab a Bomb Flower and roll it through the opening to clear the other end of the tunnel. Crawl through for a Red Rupee within the chest. Return to the main path and continue forward to the intersection. Go left to find a Goddess Cube; be sure to hit it with a Skyward Strike. Then go right to speak with a Mogma who happens to point out a lava-ringed platform.
Continue along the path some more and you’ll find a Pyrup crawl into a tunnel nearby. For this one, roll a Bomb Flower into the tunnel from a distance (or you can just get it near the tunnel entrance with flames emanating from said tunnel) to kill it. Climb the ledge further ahead and continue along the path.
Further ahead are some Pyrups again, but these are hiding in some giant skulls. To deal with these, throw Bomb Flowers into the skulls’ openings on the top. Next, climb the nearby ledges to the top area. You should soon reach another room with a chair; sit down to heal some health.
Further ahead is another Pyrup residing in a skull, but this one has no cranial opening, so you’ll need to roll the Bomb Flower in there, or do a down-up vertical slash on it. Go further ahead and drop off of the ledge for a Piece of Heart (and likely a new Heart Container, assuming you’ve followed my walkthrough thus far).
Afterwards, drop to the path below and go to the skeleton bridge. Run across and speak with the Mogma there, who will point out the little plug in the wall lessening the lava flow. Go back across the bridge, grab a Bomb Flower, and roll it across the bridge (use the arrow for accurate aim). If you do it right, you’ll destroy the plug.
Go across the bridge and onto the above ledge, then drop to the area behind it. Go around to find a few air spurts. Jump into the right one to land on the above ledge. Don’t fall in there just yet - try to aim for the Goddess Cube on one of the platforms. Another chest has, I think, Eldin Ore, which is actually fairly common around here and not totally worth passing up the Goddess Cube (the treasure within won’t be found for a long while, but it is 300 Rupees!).
Anyhow, you’ll be in a mini-dungeon at this point. Note that you can go into an eastern alcove from the entrance room to return outside and re-jump to a missed ledge. Finish collecting treasure here, then examine the Bird Statue before continuing deeper into the cavern…
As you go along the path, speak with the Mogma to be pointed to a room with many Bokoblin inside, with the leader atop a wooden ledge on the right side as you enter. You can continually defeat the endless stream of Bokoblin if you feel you’ll get some extra hearts for doing so, but you’ll eventually have to defeat the leader atop the aforementioned wooden ledge. Defeat any remaining Bokoblin, then go back and speak with the Mogma.
As a reward, you’ll receive the Digging Gloves , which allows you to dig up things from soft patches of dirt, such as the one soon to be pointed out. Dig around here to reveal an air spurt; ride it to the higher ledge. Go to the fork in the path and take the left path. Dig up the air spurt and fly to the higher ledge. Climb the ladder to reach the above room. There, defeat the Bokoblin in one of the houses, and another house has a chair to sit in if you want to refill some hearts, I think.
Nearby, there are three tunnels in the wall. Take the middle one to land near a chest; open it for some Eldin Ore . Jump off of the ledge and look around the corners - one has a Rupee-filled dirt patch. Return to the Mogma from earlier, use the air vent, then go to the fork and right.
In this room, you’ll find quite a few of the paths being blocked by some Pyrups - the Pyrups are in some tunnels and spitting fire, so you’ll need to roll a Bomb Flower in there. You’ll find a patch of them to the right of the entrance, and another in the northwest corner of the room. Also be sure to Bomb the large crack on the northern side of the room to find a Silver Rupee !!
Afterwards, exit to the east of the room and dig up the vent in the nearby area. Fly up to the ledge, then go into the nearby whirlwind to leave the mini-dungeon.
Upon exiting, go along the path upwards and speak with the Mogma. He’ll point out a gap to you. Ignore it for the moment and use the nearby Bomb Flowers to destroy the rock blockade nearby; this creates a shortcut back towards the bone bridge from earlier. Afterwards, approach the aforementioned gap to create a bridge. An unknown person will speak with you shortly, then leave. Go across bridge and examine the nearby Bird Statue.
Afterwards, go westward, up the hill. You’ll need to slash at a few Fire Keese as you do. Further along, you’ll need to hop across some lava to a steep hill. Dash to the platform nearest the bottom and defeat the Bokoblin nearby.
Go to the nearby Bomb Flower ledge and throw it down the hill, towards the rock blockade, for a future shortcut. Also be sure to do some digging here for Deku Seeds. Return to the initial platform you ran to and equip the Slingshot. Aim it further up the hill, and above the rock-wielding Bokoblin; if you hit it, it will drop the rock and effectively be killed. Reminds me of Dig-Dug. :P
Afterwards, dash further up the hill and climb onto the ledge the Bokoblin from earlier was on. Go further along the path to find a few more Bokoblin. Defeat those on the ground first, then put a Bomb Flower at the base of the wooden watchtower.
You’ll soon knock it over, also effectively killing the Bokoblin. Defeat any remaining enemies, then go across the gap, using the tower as a bridge. Also that, before going across, you’ll be able to Bomb a rock blockade to be able to play a mini-game, Thrill Digger. The basics are explained inside; I’ll leave you to it.
Anyhow, go across the tower/bridge to the vinery ahead. Climb it, grabbing a few hearts beforehand if needed, then go along the path. You’ll fight a huge Red Chuchu on the way.
Eventually, you’ll reach another steep hill, much like the previous one. Go up the platforms. Nothing much to note, really. When you reach the highest of the WOODEN platforms, shoot the Slingshot further uphill to hit the Bokoblin with rocks, killing them as before. Then dash uphill, climb the ledge, and approach the temple.
As you do, you’ll eavesdrop on a conversation between a couple of Mogmas about a buried key. There actually are FIVE PIECES of the key. Fi will make them a Dowsing option for you, so yay. Let’s begin.
Go to the left of the temple and dig around; one of the mounds has a Key Piece. Next, dig in the corner to find a vent. Grab a nearby Bomb Flower and toss it into the aforementioned air vent to clear the blockade. You can reach a Goddess Cube in this manner; be sure to hit it with a Skyward Strike. Drop back down afterwards.
Nearby is a ledge, with a steep hill and tower down from there. Near the ledge, you’ll find some Bomb Flowers. Toss one down towards the wooden tower. Once you knock over the tower, go down and dig to find a Key Piece. You’ll also find what may look like a strange flower – it is actually a Pinwheel. Just note its location for now with a beacon or your memory or something, as you cannot get it yet.
Dash back uphill and look down the very large hill in front of the temple you ascended a few moments ago. Take one of the nearby Bomb Flowers and toss it down the left side of the hill to, hopefully, remove a rock blockade. Go into the newly-revealed alcove to find a dig spot, in which you’ll find another Key Piece.
Return to the temple entrance and head east. Defeat the nearby Bokoblins. Afterwards, use one of the nearby Bomb Flowers to knock over the wooden watchtower, creating a bridge and one more Bokoblin in your kill count. Ignore the bridge for a moment and go east. You’ll find an incline going down. Follow that path to another Goddess Cube. Activate it, then go across the downed watchtower. Go further along the path, defeating some Fire Keese and a Red Chuchu as you do so.
Further along, you’ll find a gap. The bridge is uncrossable, so go to the left and hang from the narrow ledge. Go to the right to the platforms. Dash, run, and leap across to the vinery. Here, climb in a counterclockwise(ish) manner, using the Stamina Fruit when you arrive at them. Once you reach the ledge, let go of the vines and step onto the nearby switch in the cave, making a bridge.
At the bottom, go around the path and jump to the central platform. You’ll notice a Bomb Flower nearby, as well as a lava plug in the nearby wall. Throw the nearby Bomb Flower at it to drain the lava from the room. Then roll a Bomb Flower along the slope there so as to blow up the rock blockade there. Once you do so, dash across to find a dig spot containing the fourth Key Piece.
Go back across the incline and leap to the platform with the Stamina Fruit . Go to the right and grab the Bomb Flower . Step into the room behind it and blow up the rock blockade to create a very useful shortcut. Next, take nearby whirlwind to go back near the super-hot-lava room. Go back through and down the incline.
When you’re going down the incline for the second time, take the RIGHTMOST of the air vents. Upon getting on the platform, jump off of the opposite edge, then continue dashing downhill, taking the right path to the next platform below. Here, you’ll find two air vents that alternate. Time your jump so as to go all of the way across to find the final Key Piece within the dirt there.
Now, go to the bottom of the incline and go along the path to the large whirlwind from earlier. After landing, backtrack towards the temple. Examine the Bird Statue, save, and open up the Earth Temple for your next dungeon.