SpyTech: The Underwater Wire Tap

Operation Ivy Bell was a decade-long US Navy intelligence operation beginning in 1972 that successfully tapped a Soviet undersea communications cable in the Sea of Okhotsk. The USS Halibut, a uniquely modified nuclear submarine, used saturation divers to place a massive inductive listening device on the cable without piercing it. The tap recorded unencrypted Soviet naval communications and yielded intelligence credited with aiding SALT II negotiations. The operation was compromised in 1980 when former NSA employee Ronald Pelton sold the secret to the Soviets for roughly $35,000, ultimately receiving a life sentence. Later operations used radioisotope-powered devices capable of storing a year's worth of data, with multiple submarines continuing similar missions.