Also note that all you have to do is leave the room and come back in and you can get it again.).  Go through the wall on your right, kill the mummies (stun them with Song of Sun if need be) and get the chest containing the compass.

Exit back to the eye laser room and go straight through the wall on the other side.  You'll end up in a big room with two Deaths swinging giant scythes around the room (it's not enemies, it's just a giant statue).  Avoiding the blades, grab all the silver rupees in the room.  Note that one is on a platform that has a hookshot target on the wall above it, so use the hookshot to get to it.  Now go through the alcove it opened and get the small key.  Return to the eye laser room and use a bomb to blast open the remaining wall leading North.  Go through the locked door.  In this next passage watch for round small shadows on the ground.  They are Skulltulas waiting to drop on you.  Kill the three Skulltulas and drop down the ledge ahead and you'll be facing some dropping blades.  Dodge the first blade, kill the Skulltula, then go past the second and keep following the tunnel.  Now you'll be in a huge room.  Take off the Hover boots if you're using them, otherwise you might slide into a blade.  Jump over the pit, dodge the blade and jump over the next pit, dodge the second blade and jump over the pit, and just before the third blade watch out for a flaming skull to try to get you. Kill it then dodge the final blade.

Now on this island you'll have to kill a Stalfos.  Once he's dead, play the Song of Storms in the middle of the island for a Big Fairy.  Put your Hover Boots on. Facing away from the last falling blade, turn left and use your lens to see an invisible platform.  Hover on over it and the next platform, turn right, and hover on over to the door there.  Go through and use your lens to see the big spinning scythes thing.  Kill the Shield-eater and look on the walls to find 3 bats to kill.  Kill them and the door will open.  Go through it to kill a gold skulltula, open a chest for  some rupees, and open the invisible chest using the lens for some arrows.  (Yes, that was just for two stupid treasures and a gold skulltula but I didn't want people complaining that I'd missed some treasures).  Now head back out and hover back to where the Stalfos was.  You can use the Song of Storms for another Big Fairy now if you want.

Wait until the platform in front of you falls and hover forward as far as you can go to land on it (it's farther than it looks).  Then wait for it's highest point (you'll have to time it) and hover over to the next big island.  Collect all the silver rupees here (there's on inside that eye laser thing so kill it) and go through the door that opens.  Follow this passage to a room with falling spikes.  Use your lens and look at the right hand wall to see a movable block.  Pull it out onto the face tile and then push it in front of you and it will keep the spikes from hitting you.  Once it's on the second face tile walk around and start pulling it until it's on the third face tile.  The treasure box in the cage to the right has arrows.  Climb up on to your block now and hover/hop to the ledge on your left.