From Zelda Wiki.org
The
Isle of The Dead is an island that can be found once you have obtained the Northeastern Sea Chart. The isle is notably shaped like
King Mutoh's head. Located on the Isle of The Dead is the Sage's Graveyard, the Phantom Hallway (located in the isle's pyramid), the Black
Rupoor Maze and many secret passages under the surface of the island. Living dead that can fling their bones at you as they roam the island, searching for prey. Found in the Phantom Hallway is a Knight's ghost who opens the way to the Regal Necklace used to calm the cyclone blocking off the
Isle of Ruins.