I'm assuming you mean the water temple in Ocarina of Time?
That's the hardest one :P there's quite a few cheat vids on YouTube. Remember to do things methodically and check behind all the chests. Use iron boots to avoid currents. Your shadow doesn't have a long sword or a hammer like you :)
Beat the first three levels. Forest Temple, Goron Mines, and Lakebed Temple.
his in a room on the ceiling
in the main room
No he is not in the temple but after you beat Lake Bed temple he is in a cut scene after you beat the temple so WATCH CAREFULLY.
After beating lakebed temple, you will have to beat the temple in the desert. Though it isn't the end just yet.
kill the lakebed temple boss or collect enough heart pieces
you need to go to the lakebed temple in lake hylia
For the first part, use the clawshoot to pull Morpheel's eye out. For the second part, chase after him and use the clawshhot to pull yourself to his eye and attack it.
The Frog Toad is the miniboss of the Lakebed Temple. After defeating it, you get the Clawshot, which is the dungeon item.
http://uk.gamespot.com/features/6162248/p-15.html Should Help :D
the desert temple Arbiter's Grounds
After you beat the water temple.