Water Temple (Ocarina of Time)
The Water Temple is the sixth Dungeon in Ocarina of Time. It is widely considered to be one of the hardest, not because of skill needed to defeat the enemies or the boss within it, but because of its puzzle-like design and repetition to finally complete it.
Two items are required to enter the Water Temple - the hookshot from Dampé's Crypt, and the Iron Boots from the Ice Cavern. Completing the latter also gets Link the Serenade of Water warp song, which greatly speeds travel to Lake Hylia at the southernmost point of the map - the Triforce Pedestal at Lake Hylia is situated directly over the Water Temple, on the small island in the middle of the Lake. While not strictly essential, using a bottle of Blue Fire to unfreeze King Zora will have him give Link a free Zora Tunic, allowing him to remain underwater with the Iron Boots indefinitely and make aspects of the Water Temple much easier.
To enter the Water Temple itself, Link should enter the lake - note that, until the Water Temple is cleared, the water level in Lake Hylia in Link's adulthood is greatly lowered - on the north side of the island with the Triforce Pedestal while wearing the Iron Boots, and use the hookshot on the locking bar over the door. The hookshot will pull it out, releasing the door to open and allowing Link to enter the Water Temple.
This dungeon has three main floors with a huge pillar in the middle that serves as the main room. Hidden inside the dungeon are three squares painted on to walls with the Triforce on them, and these are used to control the level of the water. If Link plays Zelda's Lullaby next to one of these plaques, the water level inside the dungeon raises to the floor that he is at.
In addition, there are many wooden blocks or other items that move and have different properties when they are underwater or not, so the water rising helps to uncover the next passageway to finish the dungeon. At the end of the dungeon, the boss, Morpha, is revealed as a small nucleus that has complete control of water. After Link defeats Morpha, all the water that it had stolen from Lake Hylia fills the lake back up again, restoring the lake's beauty. Link is rewarded with a Heart Container, and bestowed with the Water Medallion from Ruto. The song used to teleport to this dungeon is the Serenade of Water.
#72: On the lowest level of the main room, walk through the south path and bomb the floor. Travel to the next room, step on the switch, and Hookshot over to the target. Hit the crystal switch and snag the Gold Skulltula. (NB: In the Nintendo 64 version of this game, the crystal switch is behind the gate, and can only be hit with a Spin Attack.).
#76: In the area shortly before the chest with the Boss Key, there is a small waterfall with a Skulltula hiding behind it. Stand on the ledge and inch forward to the edge of the floor. Look to the right to find a Skulltula. Use the Longshot to defeat it and snag the token.