Loss of USS Thresher (SSN-593) 10 April 1963

0859336uss thresher release photo

Fifty years ago today, the nuclear fast attack submarine USS Thresher SSN-593 sank 220 miles east of Boston, MA.   Thresher was commissioned in April, 1961, the first in a new class of “second generation” SSNs, far quieter and more capable than her predecessors.   On 10 April 1963, Thresher was operating with Submarine Rescue Ship USS Skylark (ASR-20), undergoing post-refit dive trials.  Just after 0900, Skylark received a garbled transmission indicating a problem aboard Thresher, that she had a positive angle and was attempting to blow ballast.   What we know now is that the attempt was unsuccessful, and Thresher continued to descend.  Reaching crush depth, the submarine imploded.   All hands, 108 of ship’s company and 21 civilian contractors were lost.


What was pieced together in the extensive Navy investigation determined that the tragic chain of events almost certainly started with a brazed salt-water piping joint giving way, spraying and shorting out a reactor control panel, causing a “scram”, a reactor shutdown.  Nuclear submarines, unlike their diesel counterparts, drive themselves to the surface or submerged using power and angle of attack, “flying” in the water, as it were.  Without propulsion, Thresher could not drive herself to the surface.   Thresher attempted to blow ballast, but ice forming in the pipes of the main ballast tanks thwarted the attempts.   At 0917, Skylark received another garbled transmission with the recognizable phrase “exceeding test depth”.  One minute later, Skylark picked up the distinctive acoustic signature of an imploding hull.  One hundred twenty-nine souls died instantly.  Thresher’s wreckage lies in 8,400 feet of water, 220 miles east of Boston.


When we talk about (or for some of us, recollect) the Cold War and the effort and sacrifice this country made to keep the world from a malignant totalitarianism every bit as great as the one defeated in 1945, we should remember the men of Thresher.  God rest their souls.  Remember them today, especially, and the lives given so we could have ours.  As one widow said in a Boston Globe interview, “It seems just like yesterday to me.”

7 thoughts on “Loss of USS Thresher (SSN-593) 10 April 1963”

      1. I used to work at the newspaper just down the street from the monument. I remember reading over old stories about the Thresher sinking – it was 25 years ago and 25 years after the sinking – and how one man, he may have been a civilian contractor, was scheduled to be onboard but wasn’t able to make the trip for some reason. I never got around to it, but I always thought it would be interesting to try and look the guy up and get his thoughts after all that time.

  1. That was the plant engineer, whom the Captain sent home because his wife had been injured. He wanted to go but the Captain insisted he go home.

  2. I did my MIDN/2 cruise on a submarine. We had a flooding incident, as a result of an MBT valve failure, which resulted in an actual no-shit emergency blow, and I was in control when it happened. Every second between COW’s hand grabbing the lever and USS SUBMARINE broaching, I was thinking about those poor bastards on THRESHER and SCORPION, and in 2000 when KURSK sank, I had a moment for those poor bastards too.

  3. I remember reading an article about the ballast tank air valves being prone to icing. I don’t remember if it was in Naval History or Proceedings, though.

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