Waves are formed by the wind. The size of the wave depends on how long and how hard the wind blows. Waves break as they move into shallower waters closer to the shoreline. How waves break on the shoreline depend on the shape and slope of the ground below it.
The three types of waves:
Spilling waves:
Usually found on gentle sloping or flat beaches. They happen when the crest (top) of the wave tumbles down the face (front) of the wave. These waves are good for swimmers.
Plunging or dumping waves:
Happen on steep sloping beaches. They break suddenly and with great power, which make these dangerous. The crest of the wave moves forward faster than the base of the wave, it curls over and crashes violently down. The force can knock you off your feet.
Surging waves:
These happen on very steep beaches or around rocky areas. A surging wave may never break as it approaches. They can have strong backwashes or undertows which can carry you off into the sea.