Which breaker type features crest curling and a strong impact on a steep slope?

• A. Spilling breaker
• B. Undertow
• C. Surging breaker
• D. Plunging breaker

Answer: (D)

The key idea is how wave shape and bottom slope drive the breaking style. A crest that curls over and drives down with a strong, vertical impact happens with a plunging breaker. This occurs when the seabed is steep or there's a reef, causing the front of the wave to slow while the rest speeds up, the crest pitches forward, and a hollow tube forms that curls and then crashes. It’s the dramatic, powerful drop that characterizes plunging breakers.

Spilling breakers, by contrast, break more gradually on gentler slopes—the crest spills down the front of the wave and energy dissipates slowly, with a smoother, less forceful break. Surging breakers break with little or no curling, simply pushing up the beach and surging back. Undertow isn’t a breaker type but a current that can accompany waves.