After meeting Melari on Mt. Crenel, you continue on to the second dungeon, the Cave of Flames.
Get the Compass
Go through the east door. If you hit the Bob-ombs with your sword, they will bounce around the room and explode, but you can use your Gust Jar on them to prevent that, or, if you bought the Boomerang from Stockwell in Hyrule Town (which becomes available after you buy the bigger wallet), you can hit them with it to defeat them instantly, but keep your distance to avoid the explosion. In this room, bomb the north wall and go through.
Equip your shield and hold the shield button to raise it, and if a Spiked Beetle hits you when your shield is raised, it will flip over and become vulnerable to sword attacks. After you defeat the Spiked Beetles, a chest appears. Open it to get the Compass, then go through the west door.
Get the Map
Don't pick up the rupees: one of them is a Like Like in disguise. If the Like Like catches you, you could lose your shield—but you can buy another from Stockwell in Hyrule Town if this happens. If you have the boomerang, you can collect the real rupees and reveal the Like Like from a safe distance. Otherwise, you can hit the rupees with your sword to reveal the Like Like from a slightly less safe distance. Kill or ignore the Like Like and go north down the stairs.
Go west and follow the path until it splits. Go east at the split, then push on the mine cart at the end of the track. You will automatically get into the cart and ride along the track. At the other end, go west until you find a weird-looking wall. Use a bomb on it and go through.
Use the Gust Jar to remove the monsters' helmets, then defeat them. A shrinking portal will appear. Use it and go through the small hole in the northeast part of the wall. Keep going east through the doors, and go east through another small hole. There is a Piece of Heart that you can't get yet, and a small hole in the south wall. Go south through the small hole, then go south through another small hole to reach the next room.
Go west, then south to a small gap in the barrier. Jump down from there, and go east, making sure not to touch the flames. Use the shrinking portal to grow to normal size. Go up the stairs to the upper part of the room and open the chest to get the map.
Get a Kinstone Piece
Go south onto the platforms floating in the lava, but make sure not to stand on the platforms too long or they will crumble and you will fall into the lava. Go west to the treasure chest and open it to get a blue Kinstone Piece.
Get Rupees
Go south from the chest and step on the switch to open the door. Go east on the floating platforms, then south, but don't stand on the floating platform next to the pots. Stand on solid ground and use the Gust Jar to remove the pots that are blocking the path. Then go east to where the pots were, and follow the path to the door that you opened. Go through.
Get on the floating platform, then quickly step off before the platform crumbles beneath you. Hit a Rollobite to make it roll into a ball, then pick it up and throw it into the hole just south of the treasure chest to the north. Open the chest to get 50 rupees.
Get a Key
Hit another Rollobite and throw it into the northernmost hole so you can walk on it and pick up the pots. Go north up the stairs. Then jump into the whirlwind and go south, and float into the whirlwind that you see there. Then go east, then north to solid ground. You can press R to stop floating. Go north up the stairs, then go to the northeast corner and step on the switch. Then go to the rightmost block and push it upward. Then push the pillar with the chest on it to the west until it falls into the hole. Open it to get a small key.
Get a Piece of Heart
If the door to the north of the chest is closed, go to the northeast corner and step on the switch, then go through the door.
Go east and get into the mine cart. At the end, unlock the nearby door and go through. Walk along the tracks to reach a lever. Hit the lever with your sword to change the tracks. Then go back to the mine cart and get into it. You will reach a new area.
Go west, then north to the next room. Fall into the hole and wait for the blade traps to move out of the way, then go north. Walk east on the tracks, then lift the pots to the south and bomb the wall there. Go through and take the Piece of Heart, then go north to the previous room. Then go north to the next room.
Get the Cane of Pacci
Go north to where you can jump down from the ledge, and jump down. Go west and some Spiny Chuchus will appear. You can't hurt them when they are spiky, but you can throw bombs at them. Or you can wait for their spikes to go away, then hit them. After they're gone, open the chest to get the Cane of Pacci. It flips objects over. If you use it on a hole, then jump into the hole, you will be launched upward.
Go west to the next room.
Get a Second Key
Stand on the first lava platform, then quickly use the Cane of Pacci on the second platform to flip it over so you can walk across it. Go west and then south to approach the hole in the floor. Ezlo says to use the Cane of Pacci on the hole, so do that, and there will be spinning energy there. Jump into the hole and you will be launched upward in the direction you were facing. Do this to reach the ledge to the south. Step on the floor switch to create a warp tile and open the door. Go south through the door.
Use the Cane of Pacci on the mine cart to flip it over. Go into the mine cart. At the end, push the pillar with the chest on it into the hole, and open the chest to get a small key.
Get back into the cart, and at the end, go through the north door. Go north to fall off of the ledge, then use the key on the door. Go down the stairs that appeared.
Go east and use the shrinking portal, then carefully walk past the traps. You can press R while moving to roll past the traps. Go west through the archway, then go west to enter a maze. Go through the maze and use the shrinking portal at the end. When you try to go back through the maze, the red things (Chasers) will activate and try to chase you when you're in their path. Use gaps in the blocks to avoid the Chasers, and make your way out of the maze. Flip over the mine cart and get in, then at the other end, flip the switch to change the tracks, then get back in the cart to get to a new area.
Hit a Rollobite, and you can pick it up and throw it, but don't put it into the hole in the top-left part of the room. You will need to throw all four Rollobites into the holes in the bottom-right part of the room so you can pull the pillar with the switch on it. When you have pulled the pillar far enough, you can push it into the top left hole, then hit it to open the path. Go south past where the barrier was, then go up the stairs and keep going north to reach the next room.
Fall off of the north end of the ledge, then open the chest to get a blue Kinstone Piece. Push the uppermost block to the right. Then go south and use the Cane of Pacci on the hole, fall into the hole, and go to the left to reach the ledge up above. Open the chest to get a green Kinstone Piece. Then fall off of the ledge and go east to the next room.
Hit the flames with your sword to get rid of them, then stand north or south of the non-moving lava platform, and use the Cane of Pacci on the spiky moving platform. (If you stand in the wrong place, you'll flip over the non-moving platform instead.) When the moving platform is going north and it stops next to the non-moving lava platform, walk across the lava platforms onto the moving one. When it reaches the top, walk east onto the solid ground where there are some flames to the right. Cut through the flames and step on the switch to create a red warp tile. Then use the Cane of Pacci on the spiky platform that appears, and use it to go back across to the west side of the room.
Flip over the spiky platform again, and when it's moving south and stops next to the non-moving platform, walk onto the moving platform, then look south and use the Cane of Pacci on the spiky platform there. Get on that platform when you reach it, then look east and use the Cane of Pacci on the spiky platform there. Use it to reach the solid ground to the east.
There are pots to the east of where you're standing. Use the Cane of Pacci on them to flip them over, then look north and flip the spiky platform over. Walk onto it to reach the solid ground to the east, where the pots were. Go to the east side of this solid ground, flip over the other spiky platform above you, and walk onto it. Then look east and flip over the next spiky platform, and make your way across until you reach the easternmost platform. Go north from that platform to reach the next room.
Go up the stairs on the left, then go north, then east to fall into the hole. If you want a green Kinstone piece, go east to the next room, then go east and avoid the traps to reach the treasure chest, which contains a green Kinstone piece. Then go west to the previous room. Use the Cane of Pacci on the uppermost hole and use it to reach the ledge on the left, then fall off of the west side of the ledge. Defeat the Keese if needed, then use the Cane of Pacci on the hole, and use it to go north into the whirlwind. Float north to reach the ledge, then go east to the next room.
Go east to reach another whirlwind. There are tiles on the floor below. Jump into the whirlwind, then float along the path that is marked by those floor tiles. You will reach a ledge to the southwest of the whirlwind. Go west to the next room, and continue along the path to reach the room full of lava.
Jump into the whirlwind, then go south, making sure to go around the stalagmites that stick up from the lava, since they block your path. Land on the solid ground to the south, then use the Cane of Pacci to reach the whirlwind on the left, but before you start floating west, you might want to float south to a ledge where there is a treasure chest that contains 100 rupees.
Then go back down to the hole and use it to reach the whirlwind, and this time float slightly northwest to where there is a hole surrounded by flames. Use the Cane of Pacci here to reach the ledge on the left, then get in the whirlwind at the south edge. Make your way west, using the whirlwinds along the way to keep floating. You can land on the solid ground in the southwest part of the room to find a chest that contains a green Kinstone piece.
From there, use the Cane to reach the whirlwind to the north, then float northeast to the next whirlwind, and go northeast from there to reach a ledge where you find a chest that contains the Big Key. Go north and fall off of the north edge. If you need hearts, you can cut the flames. When you're ready, look west and use the Cane of Pacci to flip over the moving spiky platform, and use it to reach the boss door to the north. Go through.
Gleerok
Break the pots in this room to get recovery hearts if needed. Then when you are ready for the boss battle, fall into the hole.
Throughout the battle, Gleerok will spit flames that turn into flames on the ground. You can cut them with your sword to get recovery hearts. If one of Gleerok's flames hits you before it turns into flames on the ground, you will catch on fire and will run automatically, so try to run toward a wall to avoid falling in the lava if this happens.
To defeat Gleerok, you need to flip its shell over with the Cane of Pacci, but its head and neck will block the beam, so you need to press R to quickly roll around the room until you are next to or behind Gleerok. That way, you can use the Cane of Pacci on Gleerok's shell without hitting its head or neck. However, you will also need to wait until Gleerok's shell is not glowing brightly, which it does whenever Gleerok is spitting a lot of flames. Once you flip over Gleerok's shell, run across its neck to reach its back, and hit the jewel in its back repeatedly. After a while, it will start to sink down into the lava, so quickly run back across its neck to reach solid ground. The lava will temporarily expand, so stay near the wall to avoid it. Stones will fall from above, so watch out for shadows, and keep moving. When Gleerok reappears, it will spit a lot of flames, so avoid being in front of Gleerok at this time.
Repeat this strategy until Gleerok is defeated. Go north to find a Heart Container and a warp tile to exit the dungeon.
Continue On
Outside of the dungeon, use the shrinking portal, then go east into Melari's Mines. Talk to Melari to get the White Sword. Before you move on, some of the Minish in the mines may have Kinstone fusions, so check with them if you're interested. When you're ready to move on, your next destination is Hyrule Castle, where you can find the Elemental Sanctuary. This is where you can infuse the Picori Blade with the two elements that you obtained.