In this interesting room, slide down the ramp and then climb up the fence.  Climb up to the top of the fence and kill the two bats there, then drop down to the platform just below you and push the movable block off of the edge.  Then fall down and land on the moveable block and you'll be shot up into the next room.  Go through the locked door here into the green room.  Climb up the ledges and kill the little torch slugs.  Jump across to where you see a white diamond thing and a movable block.  Push the movable block off the side, then drop down and pull it until it stops.  Climb up onto it, hop over to on top of the Goron's cage, and climb up the fence.  Now walk forward all the way until you hit the wall, and stand on about the forth tile from the cliff edge.  Get out a bomb and throw it towards the edge.  It will drop down and set off that diamond thing (it's a switch) which will make the pillar of fire temporarily disappear.  Climb up the fence where the pillar of fire was and go through the door that's up there.

Now you're in the big boulder room.  Turn right and keep going that way, dodging boulders, until you find another caged Goron.  Get his key.  Now as you exit his cage follow the left wall past a locked door (don't go through it) until you reach the other side of the room and the second caged Goron of this room (he's through a door that's in an alcove that may be hard to see).  Now on the way out of this room hug the right wall until you find that locked door and go through it.  Here you'll have to carefully walk across a walkway.  If you look high above the blocked door you'll see a gray eye tile.  Shoot it with an arrow to unblock the door.  Through the door is the Dungeon Map.  Back in the narrow walkway room, go through the locked door.  In this next room walk along the stone path and jump over onto the fence.  A flame will follow you.  Just hurry forward hopping over to the next fence until you reach the unlocked door on the other side.  Go through it.

Now you're on the upper level of the big boulder room.  Hop onto the platform in front of you and kill the torch slug, then use a bomb on the crack in the floor and climb down.  Down here you can rescue the Goron from the green room and get another key, not to mention an easier way up later in case you fall down somewhere.  Now climb back up and hop a few ledges to get to the switch that's near you.  This switch will free a Goron on the other side of the big boulder room.  Hop ledges and make you way over to him and get his key.  Now that you've got 2 more keys hop your way back to the door you came in.  Look high up and to the left when facing the door and you should see a high ledge.  There is a secret area up there.  Play the Scarecrow's song and hookshot to the scarecrow.  Turn around and hookshot to the small floating platform.  It will elevate you up to a secret area.  Go through this area and you'll pop out in a donut-shaped room where the Megaton Hammer is.  Step on the switch and hurry to the treasure chest (use your hookshot to get past the steep cliff).  Open it to get 200 rupees.  Go back down and go through the door back into the fence room.