Okay, so right after you've gotten the big key...
"- Walk down to the southwest side of the room and drop down a small pit. Defeat the two helmasaurs that are found here and open the treasure chest to get a red rupee. Grab onto the grading that is on the ceiling. Grab onto the grading near the north side and lower yourself down below the fan that has been turned off.
- Once you’ve lowered yourself all the way, look at the ceiling to the north in the floor below and you’ll see a chandelier. Grab onto it and equip the iron boots. The weight of the boots will cause a fan to turn on, but it is actually blowing out of this room, not in it. Drop down to the bottom of this room and you’ll be in the center of the city once again. Go through the door to the north.
- With the fan turned on, platforms with grating will be rotating around. Claw on over to the first spinning platform and from there, just keep grabbing onto the grading as you head across the area. Once you reach the last spinning platform don’t fall down. Grab onto the grading that is near the fan and there is a treasure chest here. Open it to get a red rupee. Now drop down and go through the door.
- There are two more aeralfos found in this area. Defeat them just as before by waiting for them to stick their shield out and pulling them towards. Once they are on the ground slash away with your sword until they regain their footing. Then use the shield attack and finish them off with a few more sword slashes.
- Grapple onto the grating that is just above the door that you came in from. Then grapple onto the grating that is on the spinning platform. From here, use the second clawshot and hit the crystal switch against the south wall. This will make the platform you are on start to spin. There a bunch of spinner platforms in this room, so just keep clawing your way to the very top.
- The top platform with grating is not spinning. Face the north wall and hit the switch to activate the spinning platform. Grab onto the target that is against the south wall and then use the big key on the big lock. Go through the door and you are drawing near to facing the dungeon boss." -
Zelda Dungeon