[thejeff]

Actually, I take that back, everyone (to a first approximation) gets a 1 encumbrance penalty underwater. Not just the unarmored units and not just the mages.

Nor is it limited to Atlantis. I checked some indies and R'lyeh as well. Even aquatic only units. Fighting or casting underwater is just harder.

I didn't bother to check if poor amphibians get an extra 1 encumbrance on top of the poor amphibian penalty.