Turtle Rock

Turtle Rock is a dungeon found in The Legend of Zelda: A Link to the Past and The Legend of Zelda: Link's Awakening for the SNES and Game Boy, respectively. In A Link to the Past, the protagonist Link would find Zelda, the last of the maidens, here, while in Link's Awakening it was the final dungeon that he would traverse through.

It should be noted that the dungeon found in Link's Awakening is the only one in the entire series where you are required to fight a boss if you wish to enter. This will occur when Link plays the Ocarina in front of the beast's head.