The Nearly Forgotten Story of a Super-Secret U.S. Navy Spy Submarine (And What It Did to Russia)

Kyle Mizokami

Security,

The Halibut conducted some of the most classified missions of the entire Cold War.

One of the most unusual submarines of the Cold War was named after one of the most unusual fish in the sea. Halibut are flatfish, bottom-dwelling predators that, unlike conventional fish, lie sideways with two eyes on the same side of the head and ambush passing prey.

Like the halibut flatfish, USS Halibut was an unusual-looking submarine, and also spent a considerable amount of time on the ocean floor. Halibut was a “spy sub,” and conducted some of the most classified missions of the entire Cold War.

USS Halibut was built as one of the first of the U.S. Navy’s long-range missile ships. The submarine was the first built from the ground up to carry the Regulus II missile, a large, turbojet-powered cruise missile. The missile was designed to be launched from the deck of a submarine, with a ramp leading down into the bow of the ship, where a total of five missiles were stored. This resulted in an unusual appearance, likened to a “snake digesting a big meal.” Halibut also had six 533-millimeter torpedo tubes, but as a missile sub, would only use torpedoes in self-defense.

Halibut was a one-of-a-kind submarine. At 350 feet long, with a beam of twenty-nine feet, she was dimensionally identical to the Sailfish-class radar picket submarines, but her missile storage spaces and launch equipment ballooned her submerged displacement to five thousand tons. Her S3W reactor gave her an underwater speed of more than twenty knots and unlimited range—a useful trait, considering the Regulus II had a range of only one thousand miles.

Regulus II was quickly superseded by the Polaris submarine-launched ballistic missile, whose solid rocket fueled engine made for a more compact missile with a much longer range. The combination of the Polaris and the new George Washington–class fleet ballistic missile submarines conspired to put Halibut out of a job—Regulus II was canceled just seventeen days before the sub’s commissioning.

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