Looks like you've got a good handle on the different techniques there. It looks a little fluorescent for my tastes, but that's easy to alter with the Hue Saturation Brightness... controls in the Colour menu.
I'd tend to keep the land and sea on different layers, the land above the sea, and use the layer mask to define the land. If you use repeated selections with feather each time, then you're coastline will degrade over time, each time you use a selection tool with feather. Layers help you work like this non-destructively.
Looking good though.
Edit: the new version is better - not neon at all. And I have no problem with your land/sea border.