After you get the Stepladder from Dungeon 6, go get a heart container then go to Dungeon 7.
Get a Heart Container
Go to the southeast part of the map, then go north until you see a heart container on a platform. Use the stepladder to walk over the water and get the Heart Container.
Get 50 Rupees
You will need at least 50 rupees if you want to avoid permanently losing a heart container in the next dungeon, so collect rupees until you have at least 50.
Go to Dungeon 7
Go south once, then go west until you can't go west anymore. Go north, then west, then south. There is a thin line of trees on the left side of the screen, and above the thin line there are two trees side-by-side. Use the candle to burn the leftmost of those two trees. Then go north, west, southeast, and south to reach the stairs that were just revealed. Go down those stairs.
Optional: Get the Compass
If you really want the compass, go west to get it. Then go east to return to the dungeon's first room.
Get a Key
Go east to find a room with Darknuts and Pols Voices. Go east from there. The room is dark, but first you should go toward the right side of the room (while avoiding enemies) until you are standing on the stepladder. This way, enemies can't touch you. Wait until it is safe, then go through the east door.
Kill the Gibdos and Darknuts. Then push the leftmost block that is in the same row as the doors. Go down the stairs and follow the passage until you are upstairs again.
You will be in a room with a bunch of Keese. Go south.
Get the key that is in this room.
Get the Red Candle
Kill the Darknuts and Pols Voices, then push the leftmost middle block and go down the stairs that appear. Get the Red Candle. It does the same thing as the Blue Candle, but can be used an unlimited number of times per room.
Get the Map
Go back upstairs, then go north. Kill all the Keese (if any) then push the leftmost block and go down the stairs. Follow the passage until you are upstairs.
From the room with flashing Bubbles, go east. You will encounter Manhandla. You have to kill it to be able to exit the room. After it is dead, push the leftmost block. Then go east.
Go to the right until you are on the stepladder. Then use the candle if you wish. Keep using the stepladder in this room to help avoid the enemies. If you touch a red bubble, be sure to touch the blue one so you can use your sword again. When you are able, go north through the door.
Go north until you are on the stepladder, then use the candle if you wish. Kill the Darknuts to get the Map. Then go north.
Get a Second Key
Kill all the Darknuts here. Take the blue rupee, then go north.
There are a lot of blue Darknuts here. Go through the north door.
Use the Bow and Arrows to hit Gohma's eye when it opens. After hitting its eye with three arrows, it dies, and the door opens. Go north, and be careful of the spike traps in the next room.
Take the key in this room.
Go to the Dungeon Boss
Kill the keese, then push the leftmost block. Go down the stairs that appear. Follow the passage until you are upstairs in a room full of blue Darknuts. Go north.
Push the middle block north. Make sure you have at least 50 rupees. Then go east. Pay 50 rupees to make the south door open. Go through the south door.
Kill the Darknuts, then push the block that is indicated by the X below:
O O O O O O X O O O O O O O O
Go down the stairs that appear, then follow the passage until you are upstairs.
In the room with Darknuts and Bubbles, go west through the locked door.
Kill all the blue Darknuts and take the bombs that appear, then go through the west door.
Hit Gleeok's heads if they are still attached to his body. When all the heads are dead, take the heart container and go west to get the Triforce Piece.