Why do ocean waves break near shore?
Short answer
In shallow water, the lower part of a wave slows because of the seafloor. The wave steepens and topples forward.
How it works
Breaking depends on wave energy and the slope of the seabed. Waves do not reach shore at exactly the same height they had offshore.
Key point
The practical point is this: Waves do not reach shore at exactly the same height they had offshore.