The search for Titanic was a cover for a secret search for nuclear submarines it turns out. I remember the pictures when they found Titanic, they were amazing.
The Thresher was tailed by a support ship as it was undergoing trials, and they reported loosing power and sinking.
The Scorpion on the other hand is a much more interesting story. The recently declassified material (40 years old) says it was one of the submarines own torpedoes that had circled around and homed in on the vessel. But why did it fire a torpedo? Certainly not just for fun, and it had just been dispatched on a mission to spy on a group of Soviet ships near the Canary Islands…
It reeks of a classic cold war cover up.
I just love cold war history.