@IABL: There was also the towed depth charge and the towed nets & hooks which claimed some uboat in shallow waters. I guess it should be possible to model that in 3D and have some patrol units carry them so that they can "ram" you underwater. Since the AI will try to ram you and go over your position, you could be fool enough to dive only like 8 meters thinking the destroyer will run above with no hopes of damaging you - only to get rammed/caught in the extended 3D underwater part of it.
