I like the suggestions for the seal's fur - yes, it is a bit of a mess.  The water movement might pose an interesting problem without post production work.  I'm using fog and clouds for the variations in the water.  Maybe tiny bubbles to indicate movement...

Also, the sunlight coming through needs to be broken up with a mask.  I can't seem to find the examples posted some time ago... great blk/white masks for underwater lighting.

r

Never Give Up!