I keep getting myself messed up, especially in the early game, when I dig into the earth and find that, despite there not being an aquifer, there are dozens of underwater lakes hiding just beneath the surface, impeding all my building. What I think this game needs is a skill that, when used, will begin to fill in details of the rock nearby - just under the floor surface, just past a wall. They might be able to map the general path of veins, underground rivers, and so forth, before you even see them.Some knowledge of geology is already hinted at in the location selection screen - you can see the layers of rock that compose the ground in a biome, down several layers, and can even see if there's an aquifer. Budding fortresses would find great use in a geologist, plotting the underground areas before committing to a large digging project.
Vorn