Last Month the Japanese try to retrive this mod a little bit more. They played in the at 2pm CET. At the moment the gametracker,com Server Monitorring is off. Hope soon they turn it on. The ranking seems to work.
You can remove damage from water easily enough in vehicles, and they just roll along on the bottom. The problem is, there is no fog underwater and you can see for miles. Not sure if you can make soldiers go underwater, at most they would just walk along the bottom like it wasn't there. You may be able to add some type of vehicle to them like the jetpack so that you could simulate them swimming, but that would be a Bit of work.
As far as that goes, you could just do a custom sky Texture that looks like water.