This is amazing. During the breeding season, American alligators call for mates with a deep loud roar. It's preceded by a pulse of infrasound that sets the water dancing.
The phenomenon might create waves that help potential mates find the gators they like best. Or it could just be an accident, a side effect of the way their scutes separate during development. Either way, it's spectacular. [Vliet 1989, Moriarty and Holt 2011, Milinkovich et al. 2013]
Video: Ojatro Visual, Inc