Looking good so far Holdenburg. I'm not too familiar with Rob's method for blending the sea colors between deep and coastal hues, but one quick method for doing this, is to create a sea color layer below your land and set it's color to a dark blue, then create a new layer on top of that for the shallow water, and fill it wit a lighter shade of blue. then create a selection of your land, invert it and, on the shallow water layer, hit "delete". This should delete all the color covering the sea but leaving the portion just beneath the land mass colored. Now turn off the selection and then apply a Gaussian blur to the shallow water layer. I'd experiment with px on the Gaussian blur and perhaps try duplicating the layer till you end up with something you like.

Cheers,
-Arsheesh