Vigilis has a couple of interesting posts (here, and here) on the Scorpion (SSN-589) loss. I confess a particular interest in Scorpion and Thresher (SSN-593) details, since I worked part-time for the office (actually, it was a one man show) which was responsible for declassifying information about radiation from the reactor and Scorpion's two nuclear weapons. In fact, I posted on this back in May, around the anniversary of her loss, when these stories routinely appear.
The Thresher story is well known, and all submariners know the sweeping changes the loss of that vessel brought to the submarine force, both procedurally in maintenance, and in operations.
The Scorpion story still remains a mystery, because the pieces have had to be recreated from only the evidence, with no eyewitness (or semi-eyewitness) accounts to guide us.
Vigilis points to former Houston Chronicle writer Stephen Johnson's account in Silent Steel and other information detailed by Johnson to attempt to lay to rest the theory that Scorpion was sunk by a Soviet torpedo attack. I think Johnson is right to attempt to lay the enemy attack idea to rest. It's a ludicrous thought, for many reasons, detailed in Johnson's Sinking the Myths. While Johnson lays out a case that there was no torpedo explosion, I believe his arguments using the sonar data are more compelling than the debris field. The Board of Inquiry, perhaps swayed by John Craven, felt that the Mark 37 torpedo batteries and the test sets used with the torpedoes were capable of setting off a hot running torpedo, and had, in fact, done this on other submarines. Johnson, and others who don't believe this theory are quick to say that it would be easy to shut down a hot running torpedo. In fact, even with the more modern Mk48 torpedo, a hot running torpedo required quick action by the ship's control party and the torpedo room. My own submarine experience says to me the danger was real and this wasn't a "routine" event, this was that one time occurrence that we all dreaded. I think the fact that the operations compartment was obliterated points to that compartment as the point of explosion.
We have the Board of Inquiry findings conveniently transcribed for us, here. There are some who disagree with the BOI and their ability to discount the bubble pulse problems with the torpedo detonation. However, the Navy has never really wavered from this theory, that a catastrophic event, likely a torpedo explosion, external to the pressure hull, caused her loss.
Unfortunately, we'll never know.