http://www.straightdope.com/classics/a1_228b.html
The Master was perhaps a trifle too dismissive of this concern. I understand that the Navy still checks up on the wreck of the USS Scorpion from time to time; what about the Thresher? Was the Russian submarine Kursk’s power plant recovered intact? What are the best case/worst case scenarios for a major nuclear submarine mishap? Anything left underwater long enough will eventually break open, I presume - what happens then?