I extended the dark shadow at the base of the wave quite significantly (compare Photo 5 with Photo 4), up the wave. Notice how I've also darkened the tones on the top of the breaking crest of the wave, not just below it. This is so that when I paint the white foam later (see Photo 8), there would be some shadow below it.
Then I added some white to the top of the wave, reducing the shadow (Photo 6). Next I started to create a mid-tone between the dark shadow at the base of the wave and the light tone at the top by adding some cobalt teal to the front of the wave.
