Walk a few steps toward the stairs, and Tetra will give you the Pirate's Charm to keep an eye on you. Climb the stairs, pick up a barrel to hide inside and go ahead while avoiding the searchlights. If you're brave enough, pick up the red rupees. Go south and climb all three stairs. Then you can leave your barrel, go right and open the door. Swing across using the rope and pick up the Map from the chest. Then jump down to the lower floor and walk on the switch surrounded by barrels to open a door. Get in, open the chest and you will find your first Piece of Heart. Get into the hall and let yourself get captured by the guards.
In your cell, jump on the table, then on the shelves, toss the pot and crawl into the passage. You end up in the room where you found the Map. Swing across using the rope and leave from the door on the left. Once out, go left and talk to Tetra. Climb the ladder, toss the pot containing weapons, pick up one and go fight the guard, as a result the first pair of searchlights will be switched on. You can also raise your shield and pick up the weapon that held the guard. Jump north-west (you will see a ladder in front of you), climb the ladder and hit the guard to switch off the second pair of searchlights. Climb down the ladder and follow the passage going down to get in a corridor with two doors. Open the door to your left (east on the map), get the Compass from the chest, then swing across the room using the rope and open the next door. If you fall down, get out quickly, let yourself get captured by guards, then leave the cell and come back.
Go left, walk up the path and climb the ladder. Get rid of the third guard to switch off the last remaining searchlights, then climb back down the ladder and go back to the passage. Open the following left door (north of the map), walk across the room, open the door and go right. You will get another message from Tetra. Go to the other side, push the crate down to make it fall (if you need a shortcut later) and open the next door.
Take the barrel and walk carefully. Walk up the stairs and open the main door. Walk up the outer stairs of the fortress and take another barrel. Get on the circular passageway towards the top of the structure, and stick your back against the walls to get past the two ledges. Go further ahead and you will see your sword! Go pick it up quickly, then fight the guard and pick up the (one of the Fortress guards must drop one). Open the door, Aryll is there with more children! After taking a few steps, the huge bird will grab you and throw you at sea outside the fortress.
Almost drowning, you will meet the King of Red Lions: your brand new talking boat! He will tell you everything there is to know about Ganondorf and the legend, then he will ask you to find a sail. Time to get to Windfall Island!