Go right and pull the lever next to the door to open it. Drop down and go left, past the two Skulltulas. The order in which you hit the parts of the lock is - top, down, left and right. In the next room, look under water, and note the lilypad with the gigantic roots on the east side of the room. Climb the vines and jump on it to flip it and open up the path behind it. Go through there, charging through the planks. Pick up the small key once you reach the chest, and ride the water jet back to the central chamber. Hop to the center portion and go through the locked door.
You can't go up in this chamber yet, so drop down (Use the sailcloth to break the fall).
Once the Stalmaster is defeated, enter the newly opened door and take the Whip.
Head back to the Stalmaster chamber and pull the valve in the room. Ride the water streams up all the way until you reach a door. Exit through there and jump down. Head to the east side again, walk past the first door and go further up. You can use the whip as a swinging rope when you grab those targetable posts. Swing as far as you can and take the map from the chest. Drop down and go west now. Stand on the lilypad close to the waterfall and use the whip to flip the reversed lilypad. From it you can now reach the lever on the wall using the whip.
Swim down through the now accessible tunnel. In the new chamber, kill the Skulltula and open the gate by grabbing the lever on the other side with the whip. Go right and swing over to the vines. Hold onto the vines of the rotating pillar, making sure you're high enough to cross the platform behind it (You can restore your stamina on it) and ride it to the other side. Start swinging on this post here, but turn a bit to the left, so that when you leap off, you grab the lever on the wall. Once you do that, drop down and climb back up using the vines behind you. Swing again, this time to the actual room. Open the valve to start the drain, then jump into it.
Climb onto the ledge with the bird statue. Use the Beetle to cut down the Skulltula that's the closest to the opposite wall, above the lilypad with the big roots. Swim through the opening, exit the water, and grab the small key from the patrolling guard using the whip.
Go through the door and into the water. You'll be flushed into a new area. You have to dive and leap out of the water to reach the east edge. Flip the lilypad with the whip, kill the Walltula and climb up. Once you reach the end of the path, jump down to flip the lilypad right below you and open up the path leading down. It's a straightforward tunnel so follow it.
Once you're on the other side, open the valve. Jump down and leap up the east edge again. Climb up the vines once more, flip the lilypad with the whip and jump across. Pull the lever with the whip and enter the central chamber again.
Make your way to the right via the vines, but make sure to clear the Walltulas first. Go as close as possible to the big lever, then use the whip to pull it downward.
Jump back down and enter the central statue. Go all the way down to where you fought the Stalmaster, and enter the door.
From the entrance to the room, go left and follow the path until you get to jump across some lilypads to the left (You'll have to flip the third one). Send the Beetle into the eyes of the stone demon head and activate a switch within. Now go back via the lilypads and turn left until you reach the ledge with the bomb. Using the Beetle pick up the bomb and use it to break the boulder blocking your path, on the right pillar.
Go back to the central part of the chamber and swing over to the now boulder-free pillar. Grab the vines on the rotating pillar and climb up to the top. From here, jump onto the next rotating pillar and jump off the on the ledge on the opposite side. Sprint leap towards the vines to grab them and climb up. Use the whip to switch the lever from right to left, then jump down onto the spinning platform.
Get off on the other side and make your way up. Grab some vines on the rotating pillar and ride it all the way to the left. Go up this path, sprint jump to grab the vines again, and switch the lever again. Go back now though and ride the rotating pillar all the way to the other side.
Follow this path and drop down into the next room. Grab the string and start climbing. Once the Cursed Bokoblins start following just ignore them. If one grabs you shake it off.
When you reach the top, turn left and pull the small lever to make the platform expand, allowing you to pull the large lever up using the whip. Now drop back down to the underground. Straight ahead is a valve, open it. Drop down and go left to find the Blessed Idol.
As soon as you regain control just sprint ahead and out of the hole. After the statue descends, enter the door and go all the way to the top. Put the idol into the lock and go up to the summit of the statue. Open the four valves and, once the statue has risen, enter the boss room.
Once the boss is dead, pick up the heart container and enter the next room. Hit the crest with your charged beam to upgrade your sword and finish the dungeon.
Return to the Island of Songs to unlock the path to the next trial.