Well, obviously, the character of the walls was the thing for this one.
At first, I thought it was going to have several states to it, like old etchings. This is the “second state” (the earlier being just a general poche for the solid areas without any particular density close to the walls. But, it seems done, and I don’t feel compelled to mess with it more at this point, so I’m calling it done.
This particular map has several entrance points, which seems entirely appropriate for its wandering, sprawling style. The character of the walls suggests nibbling or biting out pieces to clear the openings. It could also work as a series of islands in a wet swamp.
As is the case with most of my maps, feel free to use this for any non-commercial purpose (with attribution), or contact me if you’d like to use this on a commercial project.