Map an Aquatic Civilization

[cypruss11]

Maybe they are much more dense than water and for that reason cannot swim upwards just as us on land cannot swim through air.
A simpler way to do it i would think.

[Aegeri]

Torstan did a map like this for a 3rd party developer (Sunken Empires?). Unfortunately the supplement wasn't filled with maps like this like I was hoping for, which was a bit of a shame so I would love more maps like this. Never know when you might want something like this.