When we lived in Monterey, CA we used to watch the scuba divers suit up and spend hours exploring the kelp beds of the California coast. I can only imagine what beautiful things they saw.
I did an underpainting first using Caran d'Ache watercolor crayons deliberately letting the colors run into each other. Then I applied several layers of pastel using sticks of several brands including Terry Ludwig, Unison, Sennelier and a few Rembrandts for the small details. My favorite parts to work were the different patches of ocean water. Blue and turquoise have always been my favorite colors, so I was in my element!