Difference Between Plunging & Spilling Waves

Spilling Waves

• Spilling waves are much gentler than plunging waves. As the wave approaches the beach, the circular pattern of water motion gradually becomes elliptical and eventually horizontal by the time it reaches the sand. Basically, water from the crest spills down the front of the wave into the trough, so the wave doesn't break in the same way that a plunging wave does. Spilling waves are sometimes called constructive waves as well.

Plunging Waves

• Plunging waves are much more destructive than spilling waves. Plunging waves tend to form in places where the wave suddenly transitions from deep to shallow water, as when it travels over a sandbar or a rocky reef. The crest of the wave breaks and collapses or plunges into the trough, briefly forming a tube or barrel shape. Beaches with a steep slope generally have plunging waves, which tend to to have a much stronger backwash.

Conditions

• Although beaches with sandbars or a steeper slope tend to favor plunging waves while shallow beaches tend to favor spilling waves, the kind you'll get may also vary depending on the conditions. Waves that break over a reef, or point breaks, are more predictable than waves over a sandy bottom, which may be more erratic. If you're at the beach, one way to tell plunging and spilling waves from each other is to just watch the wave as it breaks, and see whether the crest spills or crashes into the trough.

Considerations

• If you're a novice swimmer or surfer, you'll be better off with spilling waves than plunging waves. Plunging waves tend to be stronger, faster and more powerful, and if you're beneath the wave when it crashes, then you could be in for a wild ride. Always treat plunging waves with respect. Surfers tend to seek out plunging waves, especially ones with a long tapering curl, because plunging waves are the offer them the best shot at a perfect ride.