Zora's Waterfall
In A Link to the Past, this is the home of the Great Zora, and it is also the source of the Zora's River. Zora's Waterfall is on the Northeast side of the map just south of Death Mountain.
In Ocarina of Time, Link must play Zelda's Lullaby to get through this waterfall and enter Zora's Domain. This mysterious waterfall is said to be magical. When revisited in the future, Ganondorf has cast an evil spell upon the village, and even though the waterfall on the outside is still flowing, the inside of Zora's Domain is completely frozen. There is no way to thaw it.
In Twilight Princess, the waterfall is frozen at first, and needs to be thawed out by releasing the water in Zora's Domain with a hot rock in Death Mountain.