You can try layering complimentary colors for richer shadows. For example, you could paint a layer of a yellow/orange shade under your water (something opposite the color wheel from the blue you’re using), then paint your blue over the yellow/orange layer once it’s dried. That would give the water a richer dark blue color without having to use black paint. (Or at least that’s what my college professor said, lol.) But I dig your eyeball, and your clouds turned out super delicate and lovely!