The Tower of the Gods (Outside)
Now, you have the Master Sword. This weapon is the only weapon able to defeat Ganondorf, who still has your sister captive! It’s high time to rescue her! I somewhat recommend doing a few side-quests (Pieces of Heart, increasing the magic gauge, etc.).
There are two that I want to do for sure. The first involves having TEN Knight’s Crests. You remember that you can steal them from Darknuts, so I think you can return to the Tower of the Gods to do so. If/When you get all ten, sail south-west to Outset Island.
Remember, you must have all ten Knight’s Crest to do this! Okay, go to Orca’s house (the man who gave you the Hero’s Sword, which you seemingly have trashed). Equip the Knight’s Crests in X, Y, or Z and get close to Orca.
Press the button that the Crests are set to to show them to Orca. He will become shocked and offer to teach you the Hurricane Spin. Do as he says, and you will learn the magic-using super-spin Hurricane Spin!!!
This attack will be very useful later in the game, as it can easily take out hordes of enemies in one use. Orca will fall to tears, seeing you accomplish what he could not over many years.
Okay, I was earlier talking side-quests, wasn’t I? Well, there is one more I want you to do. Sail to Shark Island, Northern Triangle Isle, or any other island where you have seen one of Cyclos’ cyclones.
Whenever you approach the cyclone, you’ll notice that the cyclone will begin to suck you in towards it, like it should. Now, equip the Hero’s Bow. Near the top of the cyclone, you’ll see a pinkish cloud - it is none other than the God of the cyclones, the brother of the Wind God, Cyclos.
Shoot him several times with arrows to make the cyclone dissipate and Cyclos will approach you. He will compliment your skill and then offer a new challenge - playing a song on the Wind Waker. Cyclos will move in directions that can translate into down, right, left, up on the Wind Waker. Play this song to learn the Ballad of Gales. This lets you teleport to any of nine spots on the Great Sea, so long as you are in your boat.
Using this song, you can travel amongst these islands without the senseless sailing in-between. Seeing as you can go to Southern Fairy Island, go there for a Bomb upgrade.
Now, then, you will probably use this song to travel to Mother & Child Isles, seeing as it is closest to our destination of the Forsaken Fortress. However, it merely teleports you inside the larger island, starting a cut-scene. This will give nothing. For the quickest route, you’ll have to travel to Tingle Island and sail north-west.