1. The problem statement, all variables and given/known data Explain, using Huygen's Principle, why ocean waves break parallel to the shore. 2. Relevant equations None 3. The attempt at a solution Okay, I know that the speed of the waves decreases as the water gets shallower. Therefore, since the frequency is the same, the wavelength decreases. The water is bent towards the normal to the shore, this breaking approximately parallel to it. But how do I bring in Huygen's Principle?