Mythbusters actually tested this. Water is effective at stopping bullets. Depending on how far in the water the target is, this is actually completely normal.

Hmm this deph was about 50 cm. But offcourse with that in mind maybe its to much job calculating deph versus penetration?

As to SkyeFyre's point I think the bullets were completely stopped at 5 feet down no matter what caliber they were firing. Please correct me if I'm wrong.

Though yeah it could be to difficult to fully simulate this affect or is something that isn't fully in the game at this point. I'm sure some of the Phsyx properties aren't in place yet or fully enabled\polished.

As others have already said bullets cannot travel through water for very far at all. If we could ahve bullets go through a few cm of water that would be realistic but if it's between full penetration or no penetration it's the latter that is the best option.

I think partial penetration *is* added. I was testing the physics of this, and it seems like most rounds will just shatter on entering the water, but a very small number will actually enter to a moderate depth, but at an extreme angle (much different than the entry angle) with significantly lowered power.

I haven't seen bullets ricocheting off the water as in Arma 2 yet, though. I could be crazy, though.

http://www.youtube.com/watch?v=yvSTuLIjRm8

none of the testet weapons penetrated. they all broke when they touch the surface of the water

I think some of the soldiers that landed in Normandy would disagree with the Mythbusters here. A show I saw on D-Day on the Military Channel talked about how rounds would go about a meter into the water before being slowed down. Also, I think for the Mythbusters, aiming directly at the water about a meter away from it would have different results than the angle and distance of shooting at someone in the water from the shore. Just my assumption.

Duplicate of #0002453.