Navigate the water full of fish and weeds. Watch for falling icicles and enter the door. In a room where you can copy off of enemies, copy from the flame wheel to get the fire ability. The next room has spikes and porcupines. Choose the upper door and defeat a swordsman to free Coo. The next road ahead has falling icicles and crumbling platforms. After a cutter knight, use the door to take on Master Green. Defeat this jellyfish and the goal will open.