Plunging waves
Plunging waves break with tremendous force and can easily throw a swimmer to the bottom. They usually break in shallow water. Low tides can increase the frequency of plunging waves. This wave type can be dangerous and is a common cause of spinal injuries.
Plunging waves may develop into ‘back-blasting waves’, which forcefully blast water and sand out the back of the wave when the sandbank is very shallow. They are the most hazardous type of wave.
A plunging wave that breaks directly on, or very close to, the shore is often called a ‘shore break’. This happens when the beach is very steep at the shoreline.
Spilling waves
Spilling waves occur when the crest (or top) of the wave tumbles down the face (or front) of the wave. Generally, spilling waves are the safest wave type for swimmers.
Surging waves
Surging waves may never actually break as they approach the shore. These waves are commonly associated with rock ledges that face into deep water. Surging waves do not lose speed or gain height and can knock people off their feet and carry them back into deep water. For this reason, they can be very dangerous, especially around cliffs, rock ledges and breakwaters.