In going "behind the art", I think this painting is a good opportunity to talk about surf in marine painting. Surf is one of the most exhilerating features of the seashore, and everyone who paints seascapes likes to try their hand at painting surf, so here are a few tips.
We usually think of surf as it breaks on an even sandy beach, in which case the waves are fairly regular and come ashore quite evenly. But a rocky shore is a very different situation. As the rocks make the shore irregular, the waves are not going to be as regular, but are going to behave according to how they hit the irregular shore.
In this painting, on the right we have a stretch of the shore that is relatively even ledge, a steep slope, but quite even. So here the wave rolls up the shore like it would a beach, except that since it is steeper, it tumbles over itself more as it climbs the rock.
We create the tumbling effect with light and shade playing in the breaker.
In the lower centre of the painting, we have surf boiling around some rocks. Since there is space between and around the rocks, the surf doesn't pile up like it does on a beach, but it swirls around the rocks.
Also note that after a wave has washed ashore and rolls back, the little streams of water flowing back down the rocks bubble and sparkle in their streamlets.
As the wave comes into shallow water it gradually becomes steeper and steeper as the water shallows until the top of the wave breaks and gives us surf. The same wave that is mostly water as it comes into the shallows becomes all surf as it comes ashore.
So, in this one painting we can see surf in a variety of its aspects. So have fun painting surf; it is challenging, but rewarding when you are done.