The Day We Lost the H-Bomb: Cold War, Hot Nukes, and the Worst Nuclear Weapons Disaster in History

When the Navy created Task Force 65, it shouldered the responsibility of finding bomb number four if it had fallen into the water. This was no small burden, and the Navy threw everything it had into the effort. On the day it established the task force, it also formed a small committee in Washington called the Technical Advisory Group (TAG). The five men on the TAG, each with expertise in salvage, oceanography, or deep-ocean work, were supposed to find technology, people, and resources that might be useful to Admiral Guest and then swipe them from other missions and send them to Spain.

Looking around for deepwater gear, the TAG found that there wasn't much on offer. The Navy, along with civilian scientists, had long struggled to explore the deep ocean. But its work, never well funded, had always lurched forward in fits and starts. By the time of the Palomares accident, Alvin, the experimental, temperamental minisubmarine, represented some of the most advanced deep-ocean technology in the world.

The idea of Alvin had been born years before, in the mind of a geo-physicist named Allyn Vine.

When the United States dropped nuclear weapons on Hiroshima and Nagasaki, Vine, perhaps alone in the world, saw underwater implications. Someday, he thought, submarines might carry nuclear weapons. And someday, one of these submarines might become marooned or lose one of those deadly weapons on the ocean floor. If that happened, the Navy would need a deep-diving ship for rescue and salvage.

After the war, while Vine worked on underwater acoustics for the Navy at WHOI, the idea of a maneuverable, deep-diving submersible continued to grow in his mind. Vine thought that such a vessel could complement oceanographic research. And soon he saw another military justification for such a sub. By the 1950s, the Navy had built a secret underwater listening system called SOSUS

(Sound Surveillance System) to detect Soviet submarines. During the Cold War, SOSUS involved a network of underwater hydrophones, positioned on continental slopes and seamounts, listening for enemy subs. Miles of undersea cable connected the hydrophones to listening stations on land. With all those hydrophones and snaking cables, Vine saw an opportunity. A deep-diving minisub would be perfect for inspecting and repairing the system. “Manned submersibles are badly needed,” Vine wrote in 1960, “to carry out on the job survey, supervision of equipment, and trouble shooting.” The Office of Naval Research, swayed by Vine's arguments, signed a contract in 1962 for the sub that would become Alvin. Alvin's curious name caused some consternation. Many suspected it was named for the irksome Alvin and the Chipmunks and considered it too frivolous for such a technological wonder. But the truth is that “Alvin” was a contraction of “Allyn Vine,” the name of the man who had first imagined the sub and had had the persistence to bring it to life. A year later, a national tragedy — one with direct bearing on the events in Spain — would prove him prescient.

On the morning of April 9, 1963, the USS Thresher slipped from its berth at Portsmouth Naval Yard and sailed into the Atlantic. The Thresher rendezvoused with the USS Skylark, a submarine rescue ship, and together they sailed toward an operating area off the coast of Boston. The Thresher was the lead ship in a new class of nuclear submarines that would dive deeper, faster, and more quietly than any before and carry a more formidable payload. The ship had completed various sea trials in 1961 and 1962, and then spent nearly nine months in Portsmouth for inspection, repairs, and alterations.

Now she was ready for a round of deep-diving trials.

On the morning of April 10, the Thresher, sailing about 220 miles off the coast of Cape Cod, dove to four hundred feet and reported to Skylark that it was proceeding to test depth. (A nuclear submarine's

“test depth” is the depth at which she is designed to operate and fight; in this case, 1,300 feet.) The sea was calm; no other ships sailed nearby. Ten minutes later, at 9:13 a.m., the Thresher sent another message: “Experiencing minor difficulties, have positive up angle, attempting to blow.” At 9:17 a.m., Skylark received a garbled message, which seemed to include the words “test depth.” One minute later, Skylark heard the words “nine hundred north.” That was the last message Skylark received from Thresher.