[krpeters]

On the subject of cold and water --

Cold benefits underwater creatures by increasing the oxygen dissolved in it for them to breathe. Heating it up allows the oxygen to escape to the air above and then the fish suffocate, the cause of many fish kills in a hot summer.

Implementing this within the present game mechanics is tricky. Underwater creatures should definitely get the "cold blooded" tag and be injured by cold if they come ashore. But while underwater, the affect of the cold on their bodies is probably balanced by the increased O2. So no penalty or bonus for cold, but a penalty for heat underwater makes some sense.