Thanks, Pyrandon!
In terms of the water coloration... I used 5 different layers (I might have been able to get away with 4). I wish I had been able to use my Tablet!!! Oi!
From Top to Bottom:
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1. Green/White clouds in Color Dodge - erased to various degrees from the "deeper" portions of the ocean.
2. Using a solid but soft brush is a slightly richer green with "wet edges" mode, I put down a "glaze" over some of the seabed to help pull it all together. My brush might have been in a special mode here... I don't recall - the idea was to lower contrast slightly and tone large portions of the water.
3. Using a medium scale brush with low/medium opacity on a layer in Color Burn blending mode, put down a lot more mottling. I /might/ have done some blurring using the Blur tool.
4. Using a large scale brush with limited opacity and a slightly darker color than the base (#5), I put down some general mottling away from the land masses, and then Gaussian Blurred it slightly.
5. Base Flat Water Color
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In addition, the land masses (sitting above the water) have 2 different "Outer Glow"s on it - One is tighter and smooth, the other is wider, with some noise, but at a lower opacity.
And there you have it!
PD