In The Legend of Zelda: Ocarina of Time can be accessed by heading through Zora's River. It is found within a cave and is relatively small for a home of an entire aquatic species, especially one as important as the Zora. Princess Ruto and her father, King Zora, can both be found here.
The Legend of Zelda: Twilight Princess
Zora's Domain returns in Twilight Princess, albeit with a different appearance for the sake of originality. It's been dramatically enlarged, and houses a much larger amount of Zora, still seemingly having the majority in the world of Zelda. In twilight, Zora's Domain is completely frozen, though the player is capable of unfreezing it by using a large molten rock found on Death Mountain that can be warped thanks to Midna's abilities. This act is considered by many as a reference to Zora's Domain in Ocarina of Time after the initial seven years - in the game, players attempted everything possible to try and unfreeze the now frozen domain, with no such luck.