Instructions
Defeat all of the enemies on the walrus's platform before attempting to free him. The quickest way to beat these enemies is to throw them off the platform using your preferred attack method.
Press and hold the "B" button and select "Chilla" to turn into him.
Press and hold the left trigger to aim. This allows you to pick a specific location to attack.
Aim at the location where one of the chains attached to the walrus connects to a large wooden pole.
Press the right trigger to throw an ice spike, breaking the chain.
Repeat this for the other chain to free the walrus.