Now that Link has the power bracelet we can get access to the Dream Shrine found in Mabe Village.
Once you have finished Key Cavern, make your way back there and to the northeast of the village, you’ll see a house with three rocks in front of the door. Pick up the rocks, throw them to one side and enter the building.
The Dream Shrine
Once you have entered the building you’ll see a bed. Go up the stairs, get into the bed and fall fast asleep. When you fall asleep you’ll be taken into the dream world. Run around the edges, killing the enemies in your way, go up the stairs and pick up the 100 rupees.
Get the Ocarina
Run through the rubber obstacle popping it with your sword and pick up the Ocarina. You can try playing it, but you don’t know any songs just yet. Throughout the game, there are a few songs you can learn to play on the Ocarina to help you on your adventures.
Learn the Ballad of the Wind Fish
Find Marin and she’ll say you have a nice Ocarina and will ask you to play along with her while she sings. Once you have played along with her she’ll ask if the song sticks in your mind, answer yes and you’ll have learned the Ballad of the Wind Fish. It’s not immediately obvious what this if for, but will no doubt come in handy later in the game.