Working for the first time ever in gimp. Have read many tutorials and have things mostly rolling along. One thing I am struggling with is my ocean/coastline. How do I create an ocean layer and have the colors lighten as they get closer to my coast line? Like this example..... http://www.1d6.com/artaria/images/artaria_map_main.jpg I have a border and coastline mask available, but every time I keep getting the reverse effect, it goes from dark at the coastline to lighter the further out you go.

Many thanks.