Now stand on top of the statue's head and shoot the switch a final time to be taken up to the next level.  Kill the annoying spider things and kill the Shield-eater with arrows then use the hookshot target in the ceiling to get over the spikes.  Go through the door and you'll find yourself at a big lake with a dead tree in the middle and a pillar on the opposite side.  The lake is an illusion.  Just walk over it and walk up to the pillar on the other side.  You can't get in the door, so turn around and you'll come face to face with...yourself!  In the form of Dark Link

Okay, this guy may seem impossible but there's a trick that makes him easy to beat.  First, stand on the island in the center of the lake and make sure he stands on it too.  For some reason, if he's standing on the island he won't attack nearly as well.  Some say it has something to do with the lack of a reflection.  You can also use the islands to either side but there's a glitch in the game that sometimes causes him to be stuck in the wall and you can't get him, so use the middle island. Anyway, once you've done that try hitting him with your hammer.  If he blocks, take out your sword and hit him once with a regular swing (NOT a stab) and he'll deflect it but then be vulnerable, so take out your hammer again and it should hit this time.  Then just keep smacking him with the hammer while staying on that island and he'll go down in no time.  If you can't get this to work use Din's Fire.

Now the lake will disappear and reveal where you really were...just a large room.  Go through the now unblocked door and get your nice new shiny Longshot.  Now look behind the chest and there's a temple of time block.  Get rid of it with the Song of Time and drop down the hole.  You'll be at the mouth of a river.  Swim down river and when you start coming close to a whirlpool, use your Iron Boots to wade past it.  If you get caught in it's pull and can't get out, try to get as far away from it is possible and then take off the Iron Boots and start tapping your B button like mad to swim away from it.  Make your way to a small platform on the left side of the river, just before a particularly strong whirlpool.  Use an arrow to shoot the gold eye across from you and a grate will open with a treasure box behind it.  Use your hookshot on the treasure box to fly across, avoiding the last 2 whirlpools, and open the box to get a key.  Go down the hallway and you're back at that whirlpool you got a key from earlier.  Now make your way back to the main room (you should know the way) and with your Iron Boots on go once again through the tunnel with the torches on either side where you met Ruto, and float up to the water level changing switch.  Play Zelda's
Lullaby to change the water level, then drop down and go back into the main room.

Go into the tower and play Zelda's Lullaby there to raise the water to the middle level.  Exit the door and go around the tower to the back.  There's a tunnel here with a grate and a gold eye below the entry.  Shoot the gold eye with an arrow then quickly use your Hookshot on the Hookshot target at the end of the hall.  Follow the passage until you hit a movable block.  Push it forward out of your way, turn left and get the key.  Now go back the other way and use your hookshot to fly up the hole in the ceiling and go down the hall to drop down back into the main room again.