The Legend of Zelda: Majora's Mask/Great Bay Temple

Walkthrough

 * Turn underwater yellow valve to enable water switch.
 * Climb on eastern lift, jump across.
 * In turbine, go to south-east exit with green/red pipes. (Map in this room)
 * Continue through east underwater exit.
 * Continue through tunnel.
 * Open underwater chest for small key. Can also open chest for compass.
 * Head into fast-moving water to return to turbine.
 * Enter north-west turbine exit, walk along red pipe to reach exit to the north.
 * Collect arrows and magic. Continue south to reach wart.  Pop the outer bubbles with Fire Arrows, and shoot the main eye.  When it runs low, it will start charging wildly.  Safest area is in a corner and sniping it with the bow once it eye opens and it turns. Defeating it retrieves ice arrows.
 * Retun to the south, freeze an octopod and climd to the central valve. Turn it.
 * Go to the south-east area from turbine. Use ice arrows to build a path to south door.  Freeze the Blue Chuchu and climb to the red valve and turn it.
 * Return to the start and turn both the red and yellow valves.
 * Exit to the north of the turbine, freezing the flow of water at the top. Freeze your way across to the green valve, and open it.
 * Head north east, surfacing to enter the demi-boss room. Use ice-arrows exclusively, it will die after 10 hits on the frog/jelly. Exit to retrieve the boss key.
 * Continue on the water path. Surface, head up the left and across the second lift, and freeze the ceiling water. Jump across and head to the next room.
 * In the far side of the room, stand on one end of the see-saw, and use fire on the ceiling ice block. Repeat for the next see-saw, and turn the green valve.  To exit, repeat for the first see-saw.
 * In the turbine, head south, turn the final valve, and enter the boss room.

Gyorg
Gyorg is a large pirhana.

Shoot an arrow at it's head to stun it. While it's stunned, dive and use the electrified ram to damage it.

When it is damaged, it will release piranhas into the water.

Stray Fairy locations

 * 1) Turtle room, light all four torches with deku stick or fire arrow.
 * 2) Water wheel room, below the first platform.
 * 3) Water wheel room, destroy the south-west skulltala.
 * 4) Central turbine, destroy western barrel as Goron.
 * 5) Central turbine, destroy urn below turbine.
 * 6) 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.
 * 1) North east of central gear, shoot urn near dexihands (in fast current)
 * 2) North east room, after freezing water source, climb on central water wheel and hookshot northern chest.
 * 3) North east room, after freezing water source, climb on central water wheel, stand on edge of diagonal fin, and hookshot southern chest.
 * 4) East room, hook shot to chest just after turning on the green valve.
 * 5) East room, below first see-saw.  Ram the barrel as Zora.
 * 6) North room, make ice path to corner and hookshot to second floor.  Open the chest.
 * 7) Before boss room, in bubble under valve.
 * 8) 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 defence, causing them to inflict only half as much damage.