My friend's older brother was on board.
I have seen implosions and they were quick. It was literally destroyed in the blink of an eye. With the exception of my great uncle Bud who was a Marine fighter pilot, I pretty much only knew Army people until we moved to Newport and even then I didn't know any Navy people, just their kids. I always found it interesting that the Navy renamed the class after the loss of Thresher.
IIRC one engineer familiar with the loss was of the opinion that the implosion/explosion started in the forward torpedo room by a torp battery explosion caused by a wire being installed backwards ("If it can be installed backwards it eventually will be") shorting out the battery.
I have read that there was a problem that forced the reactor into auto-shutdown at depth which led to uncontrolled descent. I never quite understood why the batteries didn't serve to force the planes to rise and propel the boat long enough to start back to the surface. OTOH, stuffing batteries, a reactor, a steam plant and all the rest into that small a volume was a work of art. Somebody might have decided that with their own reactor, fewer batteries were required since, "there's always going to be electricity." You do kind of wonder though why nobody felt the need to go ahead and produce all the Plutonium 238 they could make. Those would be handy to have 1200 feet down.