i saw a thread here on the seawolf and UUVs, where it was said..
http://sgforums.com/forums/1164/topics/340059?amp%3Bpage=2&page=2
There's no reliable IFF that exists underwater, nor is there a viable long range communication system. Short range is possible, but you must know where the other submarine is
quote
i just wanted to correct this and post about the aussie ADS2 system, to enable further discussion
http://www.adbr.com.au/download/Features%20Articles/V26N4-5_Sea1439-N.pdf