The Forsaken Fortress is an area in The Legend of Zelda: The Wind Waker. After you leave from Outset Island with Tetra and her pirate crew, they launch you off to the Fortress. As you're crashing in, you lose your sword. So you're searching throughout the entire fortress, dismantling the light bokoblins and climbing slowly upward. The Forsaken Fortress is also where Link's kidnapped younger sister, Aryll, is being held. As you reach the top, you find your sword. You enter a door and *gasp*! There's Aryll. But before you can save her a giant bird grabs you and takes you to Ganondorf, who throws you back to sea where you later meet the King of Red Lions.
Later in the game, you're back at the Forsaken Fortress, and you're well prepared. You can fight off the bokoblins with your own Master Sword now, and you actually get to save Aryll. Well, the pirates do. They work on taking her back to Outset. As for you, you defeat the giant bird and meet with Ganondorf. He talks a bit and then Link tries to fight him off with the Master Sword that he acquired before returning to the Fortress. But the power to repel evil has faded away from the sword, and you get shocked by Ganondorf. Tetra comes to assist you. But Ganondorf accuses her of being Zelda. Tetra tells you to pull yourself together, being that you got shocked and all, and then she gets snatched by Ganondorf! You're still trying to pull yourself together when Quill and Prince Komali grab you and Tetra and take you both to the King of Red Lions.