Thanks, Voolf! It isn't exactly meant to be a gradient; in my earlier maps in this style, I simply went with outlines as a placeholder until I figure out the real seafloor contours, and the client asked me to use the same style. If he wants me to work out the sea contours, I'd be happy to.

Meanwhile, I've been in touch with the client, and based on some feedback, I've produced a new WIP:

commission01-sizeman21-wip02.jpg

The different-colored area in the southeast is meant to be a desert, as per the client's request. I'm not completely satisfied with the effect; I may need to do something more than a simple hue/saturation shift to better suggest the area's dryness. In any event, unless I need to make further changes to anything, it's just about time to start labeling things.