There’s a bit of an alga bloom in the dock area which affects the quality of the water (Hello, chemical run off from lawn care.). We were heading out for a cruise on Mort’s boat on Tuesday and I was standing at the mast when looking down I saw this marvelously complex sickly green halo around my shadow; pukey in green, abstract art in black and white. The patterns around my head are especially interesting because clean water doesn’t do that.
dunelight 
Light touching a Byzantine mosaic.
Yes..I see it now. The light playing in the depths of the water usually does not do that. It happens when there is a lot of particulate matter in the water and on this day there was a lot of alga in the water. It was bright green.