In the detail of the wave shown opposite you may be convinced you are looking through the wave ... but this is mere illusion. My steps in painting were as follows:
1) Paint the whole canvas a thinned mix of dirty sand colored raw sienna mixed with a little raw umber and white. Adjust for a approx value 5 or 6. Let dry to the toutch.
2) With a nice runny flake or lead white with a little ultramarine and cobalt blue and using flowing figure eight horizontal hand movements create the wave tops.
3) Add some white to the raw sienna/umber mix and paint the pattern into the verticle wave surface making sure thet the lighter more intense pattern is in the shallower wave's forward edge as I have shown.
NOTE: Don't begin the painting until you see the finished article and understand all the steps ... particularly the point that to make something look behind someting else does not necessarily mean painting it that way!