If a creature is fully submerged in water, they have fire immunity 5 and lightning weakness 5. If they can’t automatically swim at full speed while moving, their power rolls take a bane.
Suffocating
During combat or under similarly stressful circumstances, you can hold your breath for a number of combat rounds equal to your Might score (minimum 1 round). At the end of each combat round after that, you take 1d6 damage while holding your breath.
Out of combat, you can hold your breath for a number of minutes equal to your Might score. Being unable to breathe after that time counts as a stressful condition, causing you to run out of air as above.