Where is Zora's Domain in Legend of Zelda Ocarina of Time?

You get the Zora Armor from the Zora Prince after saving his life. After saving his life his mother will appear in ghost form when you leave the building in which the cut scene drops you. Follow the Zora ghost and you pop up in a secret area behind the graveyard. You then get the Zora Armor from the newly opened grave after a chat with the Zora ghost.