Forsaken Fortress

The Forsaken Fortress is located in the far Northwest quadrant of the Great Sea in The Legend of Zelda: The Wind Waker, and it is where Ganondorf has constructed his temporary lair by using a portal from Hyrule under the sea. It's an ominous island, and most people tend to avoid it. The stone fortress is well-guarded with cannons, searchlights, and hordes of Miniblins, Bokoblins, and Moblins, who patrol and attack any would-be invaders. The Helmaroc King has made his home on the Forsaken Fortress as Ganondorf's servant. It was also the place where Link's sister, Aryll, was held prisoner, along with Mila and Maggie.

During his first visit, Link was catapulted to the fortress by Tetra and her crew. Upon landing, he loses his sword and is left with only his shield to defend himself. In order to reach the room where Aryll is being held, you must travel to each tower and use Boko Sticks to defeat the Bokoblins operating the searchlights. Once you are outside the room where Aryll is being held, you get your sword back and fight a sheilded Bokoblin. Before he is able to save his sister and the other girls, the Helmaroc King swoops in, grabs Link with his talons, and brings him before Ganondorf. Ganondorf then tells the bird to discard him, ergo his rescue attempt failed and Link ended up unconscious in the Great Sea.

Tetra briefly mentions to Link that the fortress previously belonged to another clan of pirates. Thsi indicates the Gerdo tribe, as many of them are still active as pirates in Phantom Hourglass. This would make the Forsaken Fortress the Great Sea version of the Gerudo Fortress.