The water from the Compass Room will push you back to the Central Chamber . Take the lower path with the red pipe to reach the Octorok Room. Climb the red pipe to get out of the water then shoot the Real Bombchu and go through the locked door.
The Chu Room
This room has a bunch of Green and Yellow Chu, defeat them for Arrows and Magic. When you’re all filled up, head into the Mini-Boss Room to fight Wart.
Look up as you enter to start this battle. Wart is basically a giant eyeball with lots of little bubbles all around it for protection. You need to blast a bunch of these off so you can shoot the eye.
There are numerous ways to do this, the Hookshot serves as a safe and simple way to grab one at a time, but tossing a Bomb or using a Quick Spin Attack repeatedly seems to be the fastest way.
Once a bunch of the bubbles are removed shoot the eye until it slams to the ground releasing all the bubbles. Quick Spin Attacks will easily dispose of the remaining bubbles.
Nock an arrow and fire when the eye is open and facing you to score the final blow. Once defeated, a chest with the Ice Arrows appears in the middle of the room.
If you are having troubles with this battle just stand in one of the corners, Wart is too big to hit you at these locations.