Can you shoot your weapon under water in cod4 I can't remember I don't think so. I know in cod 5 nads and knives work weapons don't unless your feet touch the ground and your head shoot is above the water line. So if he's using his weapon he must have something showing. Now if the water texture stops before the bottom thats a map error and I would call the a glitch but once again if his head is in the water his weapon won't work. Other that we see to many times are models that are not clipped proberly like rocks trees and vechiles that you can walk into and hide those are glitches. Thats my experience in dealing with water. Cod2 is totally different.