This part will take you up to your second visit to Dragon Roost Island
Mother and Child Isles
With Zelda now safe in the Master Sword chamber in Hyrule Castle, let's return to the King of Red Lions and go back to the world above to start the next part of the quest: awakening the two sages that can restore the full power of the Master Sword. Before we do that, though, let's warp to the island located one block south and one block east of the northwest corner by using the Ballad of the Gales. We will now appear inside an island rather than outside it, and greeting us inside the island is what appears to be a little girl but is actually the Queen of Fairies. She will now give us two fairies that will empower us with the ability to shoot Fire and Ice Arrows, both of which will come in handy during this part of the quest. Interestingly, the Queen of Fairies will flirt with Link, but the King of Red Lions will give him that look that tells him to focus on the quest.
Since the only way out of the island is the same way we came in, let's warp to another island that's close to where we want to go next. That place is called Fire Mountain, which is one block south of Dragon Roost Island, one of the Ballad of the Gales warp spots. Set your wind direction for south when you get there and start sailing. Fire Mountain is a constantly-active volcano, so get as close as you safely can to it and shoot an Ice Arrow at the gushing lava on top. The island will cool down, but it will only remain that way for 5 minutes, so we need to work fast to get what we want from inside the mountain or Link will be badly burned. Climb up the ledges that first go to the left, then turn and climb up the ones that go counter-clockwise around the mountain. At one point, you'll have to sidle across a narrow ledge. While you're ascending, watch out for the Kargarocs that will attack you. Drop down the hole when you reach the top.
Inside the mountain from where you start, take down the Fire Keese, then go across the platforms on the lava pool until you come across a space where you'll be fighting an old friend from Dragon Roost Cavern, the Magtails. Draw them away from the lava and slash at them until they're destroyed. When all the enemies are destroyed, a treasure chest will appear that will give us our next useful item, the Power Bracelet. When you get the item, the timer will no longer appear at the bottom of the screen, meaning that the whole island is now safe. Go over to the big headstone and use your bracelet-enhanced super-strength to lift it out of your way so you can head back to the beam of light that will take you out of the mountain.
The next place we want to go to is an island that the King of Red Lions has marked out on our map -- an island one block east of Outset Island called Headstone Island. Use the Ballad of the Gales to warp to Outset Island and then set your wind direction to east. When you get there, you'll see a big headstone blocking our way inside. Go pick that stone up like it was nothing and toss it away. Inside, you'll see a giant stone tablet that has six notes on it. Get out your Wind Waker and copy the notes as they are played out. You've just learned the Earth God's Lyric. When that happens, the spirit of a Zora named Laruto will appear with a golden harp, telling Link that she was the sage of the Earth Temple. She was offering up prayers when Ganondorf had her killed, so our goal is to find a descendant of hers that carries the same instrument that she does in order to awaken that person as the new sage and to open up the way into the Earth Temple.
Dragon Roost Island
With that information on hand, let's warp again to Dragon Roost Island and this time visit the place again. Here is where Link remembered Medli carrying a golden harp on her back, and as we return we will hear harp music being played. As we reenter the mail center, go through the door that leads to the three-pronged wooden platform. Once you're on the platform that's on the side of the mountain, use the Grappling Hook to swing to the ledges on the right. Climb the ladder to continue following the music, and we will see Medli so busy playing with her harp she doesn't even notice that Link is standing there. Get out the Wind Waker and play for her the Earth God's Lyric. She will faint and see a vision of herself with Laruto and the Master Sword. She will then realize that she has been awakened as the sage of the Earth Temple. She will ask you to take her to the Earth Temple, but as she leaves Dragon Roost Island with Link, Prince Komali flies overhead and watches them depart.