Here are 2 videos on painting a wave in watercolor. Following the videos are some still pics of the final demo. The point of incorporating shore rocks is to play up transparency of water. There is a bit of yin-yang in the fact that waves create the shore, but shore creates the waves. The last stage (not on video) involved clarifying rocks, using a wet sponge to manipulate the line of the white wave crest to create focal points and make it more random-natural. I also added some mauve to the green and blue in places to create warm-cool and dark contrasts. Note hard and soft edges. Along the wave-crest I also added spits, spurts, droplets and wind drift using titanium white FW ACRYLIC INK (my favorite – no other is as good).
The above are all watercolor. Here is the acrylic version: