The answer is - wavelength.
As the wave approaches the shore and it reaches shallow waters it's characteristics start to change. When the wavelength is half of the water depth than the bottom of the wave starts to drag on the ocean floor. As it starts to do this the wave starts to slow down at it bottom as it approaches the beach but the upper part of the wave maintains its initial speed. Because of this the wave becomes longer. Once it reaches the shore it crashes on it and falls apart.
Answer:
As the wind passes over the surface of the oceans, a portion of the winds kinetic energy is transferred to the water below, generating waves.The kinetic energy of the wave turns a turbine attached to a generator, which produces electricity.The wave energy is absorbed by radiating a wave with destructive interference to the incoming waves. Buoys use the rise and fall of swells to generate electricity in various ways including directly via linear generators, or via generators driven by mechanical linear-to-rotary converters or hydraulic pumps.