An extraordinary story! The HMS Vanguard and Le Triomphant, both SSBN's, collided while submerged. Both London and Paris are so far not commenting on the matter, as is usual when missile subs are involved.
http://www.guardian.co.uk/uk/2009/fe...arines-collide
(Warning: the Guardian's writer obviously has no clue about submarines and how they work.)
The way I see it, only two possibilities.
1. It was a true, real, almost unbelievable accident: Two of the world's quietest submarines just happened to be at the same place, at the same time, and at the same depth.
2. One of the two skippers thought he was actually driving an SSN, not an SSBN, and stared playing a game that ended in disaster.