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. 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.