5,000ft of water will stop them. We couldn't get them during Project Azorian, and now we know where the
sub is, it would be impossible to keep a secret what you are doing as you start sailing out there with the necessary recovery gear.
Also, the burial at sea video released by the CIA for the Soviet Sailors that were recovered is really cool and worth the watch. Makes you proud to be an American that we we do this at the height of the Cold War.