The Cannon is a piece of equipment used for firing projectiles at enemies, switches, and other targets from the water. It can be fired by pressing Z when in water. It can be upgraded to allow projectiles to hit underwater targets.
The Cannon can be found on Boracay Island. The Cannon Map leads to a secret passage under the waterfall, leading to an underground area. In the underground area there are many sand blocks. These must be dug up with the Shovel to find the buried Cannon in a locked chest.