In the Pacific Ocean, wavelengths up to 600 m have been observed, thus water deeper than 300m will not feel passage of wave. But outer parts of continental shelves average 200 m depth, so considerable erosion can take place out to the edge of the continental shelf with such long wavelength waves. When waves approach shore, the water depth decreases and the wave will start feeling bottom. Eventually the steep front portion of wave cannot support the water as the rear part moves over, and the wave breaks. This results in turbulent water of the surf, where incoming waves meet back flowing water.
Rip currents form where water is channeled back into the ocean.
Rigorous erosion of sea floor takes place in surf zone, i.e. between shoreline and breakers. Waves break at depths between 1 and 1.5 times wave height. Thus for 6m tall waves, rigorous erosion of sea floor can take place in up to 9 m of water. Waves can also erode by abrasion and flinging rock particles against one another or against rocks along the coastline. Waves generally do not approach shoreline parallel to shore.