A map in progress

[jfrazierjr]

water contours.... dark to light

Looks to me like taking a layer, setting the darkest area you want as a very dark blue and then take a lighter colour, making a contour, taking an even lighter color, and so on until you have the size of continents you want, then blurring it.

And it also depends on the map in question.

If the latter map is the source of the question, one of the things I recently discovered thank to inspiration from RobA is to copy your land layer, create a path from the selection, and then run a stroke path on that, and put that layer between your land(under land) and water layer(above water) and play with the mode (GIMP). This is especially cool if you set the brush size kind of big (and fuzzy) and then set the jitter to a big value. You then get a nice random stroke to the coastline path. Very nice IMO.

Joe