IDK. Its something on a boat. I was thinking underwater transom lights, since it looks to be a swim platform light above. IDK at all. Others said a melted light fixture cover.
It's nothing unusual just ice off from a round object, you will usally see it after a freezing rain, it can come off from buoys, round coolers, even a ball that was left out in the weather.
It's the end of May, it's 90 degrees in FL today. Is there really a freezing rain somewhere south of Alaska? It's amazing how you loose touch with weather reality when you live somewhere that has no seasons!