April 10

Perhaps the most sophisticated submarine of its day was crushed 45 years ago today off the coast of Cape Cod. The USS Thresher, a 3700-ton Permit class nuclear submarine, was designed to navigate deeper and move faster than any previous submarine. Its purpose was to hunt down and destroy missile-firing subs developed by the Soviet Union during the Cold War.

After an overhaul during the winter, the Thresher sailed to New England to conduct deep-water tests. On the morning of 10 April 1963 a design flaw -- most likely located along the steel bonded fittings in the sub’s piping system -- caused 100,000 pounds of water to spray into the sub, tilting its nose upward and shutting down the vessel’s reactor. Without power, the Thresher sank toward the ocean bottom. When it reached its “crush depth,” the submarine imploded, taking the lives of 129 sailors and civilians, whose last moments must have been unendurably frantic as they struggled to regain control of the doomed vessel. Radio operators on the USS Skylark -- a naval rescue ship assigned to shadow the Thresher on its maneuvers that day -- actually heard the submarine’s last moments, which somewhat mercifully consisted merely of the sound of metal being crushed.

The loss of the Thresher proved to be the worst peacetime naval disaster in US history. The vessel still rests in six parts along the ocean floor.

The Thresher was obliterated exactly 43 years after the Titanic left port in Southampton, England, on its way to New York.