A painterly water brush!
It needs a bit of playing around with how to place the waves and different colors but in the end one can make it look amazing!
Layer colors from deep blue and green to their lighter colors, add the foam brush in a thin line around for foam at shores or for bigger splashes make the brush big and draw a line, then a few strokes into the direction you want it to splash into. 
It will make a few random splashes.

brushes