The more I think about mats, the more I desire plain water, possibly with different shades to represent different depths when desired. Given that the ships are on the same plane as the mats, any type of land mass will always affect game play. This is significantly different from the game mats for WoG where the airplanes are not flying at the same level as the ground, so whatever is on the ground need not impact gameplay. The only land mass I can think of that I might want is a river with land on both sides. Such a mat might require too much in terms of terrain tiles to do effectively, but without having seen such tiles, it is hard to judge.

I really hope the KS mats will be plain. I think that is the best way for Ares to start - most universal.