Thresher was lost doing a test dive after a yard period due to a seawater pipe failing under the scram breakers and procedures at the time. Before subsafe and level 1 quality control QC was developed. Scorpion was lost depending on which story you believe, off the Azores Islands. One says battery well explosion and one a hot runner commander trying to make Captain. The Russians had other plans. The families of Scorpion’s crew were waiting at the pier for her to pull in. It never arrived. I knew people who served on Thresher, none on the Scorpion. A shame about the Bonhomme Richard at in any case.
I agree, I was on the Blueback. It’s to ever see a ship/boat go down.