The Legend of Zelda: Majora's Mask/Great Bay Temple
Inside this large machine, you'll need to set up switches and wheels to get through and engage the boss.
 To the first mini-boss
After the turtle drops you off, go right ahead to the next room. If you swim forward you'll see two yellow valves - one above, one underwater. Open the underwater one (push it) to create a water jet, which will serve as a stepping stone later. Get onto the right elevator (from the entrance door) once it's at its lowest point and let it carry you upward. At the top, kill the two Skultullas with your boomerangs and use the water jet to get across the pit. Follow the path to the next room.
This is the waterwheel room. Jump into the water and swim through the upper passage (due to the water flow, there's only two you can go through at this time). You should end up in a room with a few skullfish. Climb up the small platform to your left and hookshot yourself to the treasure chest containing the Dungeon Map. You can't reach either of the two doors here, so dive down and swim through the other passage (be sure to kill the two Dexihands) to get to the next room.
This room is full of Bio Deku Babas. Use your boomerangs to kill them from afar, as they can be annoying buggers. Afterwards, surface and go through the door. Use your Hookshot to get to the big treasure chest you see, it contains the Compass. Jump into the pool and get to the bottom to find another chest containing a Small Key. Surface and jump into the stream to get back to the waterwheel room.
This time, take the bottom passage. In the next room, surface and walk on top of the pipe to get to the door, unlock it with your key. Here, use the jars and Chuchus to refill, because the next room contains the mini-boss...
 Mini-boss 1: Wart
Look up to spot your foe... Wart is basically a giant eye who is guarded by lots of bubbles. He can only be hurt while his eye is open - try to get rid of the bubbles (Deku Nuts work very well and you're sure to have a few at this point) and once his eye is open, get a lot of hits in. After a few hits, Wart will release all the bubbles at once, which can be annoying if there are still very many around. His new strategy involves moving across the battlefield - try to get in some shots with your bow once he opens his eye. The best spot to stand now is in the corner, as you can not really be hit in there. After a few more hits, Wart will be history.
Open the treasure chest to obtain the Ice Arrows.
 To the second mini-boss
Get back out. Notice the red valve in the middle. Until now, there wasn't a way to get there. Swim to one of the corners, and shoot an Ice Arrow at the Octorok, which will freeze him into a solid block of ice. You can now use him to reach the red valve and open it. Dive down and swim through the passage to return to the waterwheel room. Swim through the upper passage again to return to the Dungeon Map room.
Get back to the chest you opened before. Shoot Ice Arrows into the water, which will create small ice platforms. Use these to get to the door on the other side of the room (be quick, those platforms won't last forever!). Here, to reach the red valve, you'll need to lure the lone Chuchu close to the valve and freeze it solid with an Ice Arrow. Climb up and open the valve, then get back to the room with the Compass. (You went through this before so read up if you forgot where to go.)
Again, use your Ice Arrows to create platforms in the water which will allow you to get across to the passage. Destroy the icicles and melt the door so you can go through it and meet the second mini-boss...
 Mini-boss 2: Gekko (2)
Yes, it's our old friend from the Woodfall Temple. This time, he got companion in the form of big blobs of jelly. In the first part, simply slash him with the sword. He will then go up to the ceiling and try to drop on top of you, watch his shadow to avoid the attack. When he is at the ceiling, shoot an ice arrow and the Gekko will freeze and drop to the ground. The cycle will repeat from anew. Once you got enough hits on him, he will faint.
Go through the only open door to reach the chest containing the Big Key.
 To the boss
Get back to the waterwheel room. This time, climb up all the way and jump onto the blade. You'll see a passageway blocked by a water jet - shoot an ice arrow to freeze the water jet, allowing you to pass through. In the next room use your Ice Arrows to get to the green valve and push it.
You'll now want to return to the beginning room, so go out and go through the passageway on the opposite side. If you did everything correctly, there's a new water jet, allowing you to get to the red valve. Use the Hookshot target on the ceiling to get there, and push the red valve to stop the waterwheel. Now get over to the yellow valve and push it as well. Everything in this dungeon will now flow in the opposite direction, opening a while lot of new paths!
Get back to the waterwheel room and take the upper passage (this should now be a different one than before), which leads back to the big key room. Keep following the stream and watch out, because you'll be pushed right into a set of water mines. Take the elevator up, jump onto the waterwheel, then onto the next platform once it moves to you. Get onto the path and stand in the south-east corner. In the back you'll see the water stream that powers this wheel, freeze it with an Ice Arrow and the waterwheel will stop, allowing you to walk across. Do so and go through the door at the end to get to the next room.
This room is full of see-saws. Jump down and get to the see-saw at the corner. Look up to notice a block of ice, shoot a Fire Arrow to melt it, which will push you up. Jump across to the next see-saw and do the same here. Now you can jump across to the green valve and open it. Once you've done that, get down, go to the last see-saw, and unfreeze the stream once again to be able to reach the passageway. This leads back to the Dungeon Map room.
Get back to the waterwheel room, and take the bottom passage this time. Walk up the green pipe to get to the last valve, and open it to create a water jet allowing you to reach the boss room...
 BOSS: Gyorg
Whenever you feel ready, drop down to meet a giant fish who seems to be quite hungry. This fella essentially has three attacks: he can devour you if you're in the water, he can try to knock you down from the platform, or he can launch a jump attack against you.
Stand on the platform, look where he is and shoot an arrow to stun him. Now turn into a Zora, jump into the water and attack him with the magic barrier, afterwards hurry up and get out of the water. (I hope you can handle Zora Link well, because this is quite difficult!) Repeat this cycle after a while and Gyorg will get a few skullfish to help him, which can be a major nuisance. Continue your cycle and he should die soon.
Once he is dead, get your obligatory Heart Container and Gyorg's Remains.
 Stray Fairy locations
- Turtle room, light all four torches with deku stick or fire arrow.
- Water wheel room, below the first platform.
- Water wheel room, destroy the south-west skulltala.
- Central turbine, destroy western barrel as Goron.
- Central turbine, destroy urn below turbine.
- South east of central gear, break an urn
- B1, Access tunnel between North-east and south-east chambers adjoining central gear shaft; kill all five Bio Deku Babas and open the chest.
- North east of central gear, shoot urn near dexihands (in fast current)
- North east room, after freezing water source, climb on central water wheel and hookshot northern chest.
- North east room, after freezing water source, climb on central water wheel, stand on edge of diagonal fin, and hookshot southern chest.
- East room, hook shot to chest just after turning on the green valve.
- East room, below first see-saw. Ram the barrel as Zora.
- North room, make ice path to corner and hookshot to second floor. Open the chest.
- Before boss room, in bubble under valve.
- Before boss room, in bubble within exit vent.
When you have all fifteen, return to Zora Cape and leap from the rocks to the south and use the hookshot to travel to the rest of the stray rocks. Blast the boulders with the bomb, and head inside to the fountain.
The Great Fairy of Courage will strengthen your defense, causing enemies to inflict only half as much damage.