We were at Sebastian Inlet about 30 years ago when a series of waterspouts came south not far off the beach. If I remember correctly, there were six of them. In retrospect, we probably should have run for cover, but it was so fascinating to watch them march down the coast, hit the jetty and go SPLAT! Luckily, the fishermen on the jetty saw them coming and hightailed it off.
I've never seen one since.