Sleepless Waterfall

The Sleepless Waterfall is a waterfall at the end of the Zora's River in Ocarina of Time. The waterfall lies as the final obstacle in the river Link must pass before entering Zora's Domain, of which the entrance is just behind the waterfall itself. The waterfall (and therefore, Zora River itself) flows from Zora's Fountain where Lord Jabu-Jabu dwells. It is possible to view the drop-off of the waterfall from Zora's Fountain, but unlike the trip from Gerudo Valley to Lake Hylia, jumping down the waterfall is impossible (without glitching) due to a series of stakes blocking travel.

The waterfall, and thus Zora's Domain, cannot be entered directly. Instead, Link must play Zelda's Lullaby in front of the waterfall, as indicated by the Triforce marking on the ledge just in front of the waterfall, and Navi's hint.

According to an inscription in a ledge in front of the waterfall, the flow of the waterfall serves the King of Hyrule; as such, when the King of Hyrule slumbers, so does the waterfall.

A Link to the Past
In A Link to the Past, it is possible (but not certain) that the waterfall where the Flippers are obtained is the same Sleepless Waterfall as in Ocarina of Time due to their similar placement, although Zora's Fountain is absent from the top and Zora's Domain would be unreachable behind the waterfall.