The sea water is influenced by the sea breeze and the change of air pressure, which urges it to leave its original equilibrium position and move upward, downward, forward and backward. This formed waves at sea. Wave is a kind of regular periodic fluctuation.
When the waves rush to the shore, the up-and-down movement of the lower water is hindered because the depth of the sea is getting shallower and shallower. Due to the inertia of objects, the waves of seawater are layered and more and more, and each wave is higher than the other.
At the same time, as the water depth becomes shallower, the movement resistance of the lower water is getting bigger and bigger, so that in the end, its movement speed is slower than that of the upper water, and due to inertia, the highest part of the wave falls forward and falls to the beach, becoming splashing water.