My suggestion, for now, would be to make the ocean lighter but take the current color and use that as the stroke instead of the black - gives it more of an atlas look. If you were going for satellite-style then I'd just darken everything and remove the stroke. As Sergei said, lots of potential...you already have a good grasp on what you want and a real good idea of how to do it. Everything from this point on is just style issues since this seems perfectly fine to me. Nice job, man.