Acronym for Sound Surveillance System. During the Cold War, a highly classified network of underwater acoustic sensors was deployed around the globe to monitor the movement of Eastern Bloc submarines. Originally developed to protect America’s eastern seaboard, SOSUS recorded transits through geographical choke points such as the Strait of Gibraltar and the Greenland-Iceland-Faeroes gap. The sonar arrays were eventually extended to provide coverage of much of the Atlantic and Pacific ocean basins. Linked by 30,000 miles of cables, which terminated at 22 permanent, protected facilities on land, the equipment was mounted on rigid frames corresponding to the size of a double-decker bus and deposited 3,000 feet down on the sea floor by night, safely away from hostile satellite surveillance. SOSUS was declassified in 1991 when the system had
been defeated by the introduction of the Akula-class submarine, nearly three decades after the first Soviet nuclear submarine had been detected near Iceland in June 1962 by a terminal in Barbados.
The use of hydrophones to detect and monitor submarines dates back to World War I, when the Royal Navy sank three German U-boats after they had been heard on passive devices located in shallow water.