Very nice. Nothing can beat a touch of certain death :)

Maybe the Dungeon Worlds annual can be a good start?

Won't help you build crystal cities (not sure about resources for that), but it is a nice way of mapping an Underdark-like world.

Tools -> Global Raise -> Water Level will rise the water level by the specified amount. Works fine on the mola2x2a Mars data if that is what you are using.

Looking great. Very nice work there.

The fill in the street in the second one looks a bit repetitive though.

I put it in on Malajuri, off the coast of a small island. The map looks quite tropical, so I think this is the best fit.