wave train
A series of standing waves formed where fast current hits slower water or a change in gradient, creating a rhythmic sequence of peaks and troughs that a raft or kayak rides through like a roller coaster. The most purely fun feature in whitewater — predictable, exhilarating, and usually safe.
Etymology
Borrowed from physics, where "wave train" describes any series of waves of similar wavelength. In paddling, the term is self-evident once you're in one.
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