» Fri May 11, 2012 9:50 am
It's not possible.
If you try and cast a spell, or swing a weapon, and the animation of the arm is anywhere in the water, it will not work. This is the same with NPCs.
If say you were waist deep [or lower] in a river with your feet touching the floor, and you didn't have to literally float in the water that would be the only time you could attack.
The only type of creature I think might be able to attack in the water, would be a biter (Like a Wolf) or a water based creature. I've only seen it happen a few times [With a Wolf], but it might only be a bug.