USA’s secret underwater surveillance system – microphones under the sea

Point Sur SOSUS Facility, California, USA
NAVFAC Point Sur - SOSUS Facility, California, USA
NAVFAC Point Sur – SOSUS Facility, California, USA. The facility, which dates back to the Cold War, is the only remaining stand-alone SOSUS Naval Facility on the west coast.  The facility was operational from 1958 to 1984. Photo by Manhattan Perry, March 2020.

SOSUS – the microphone spy network under the sea

Up until the late 2010’s, most people who drove down the Pacific Coast Highway in California, USA thought they were looking at a US Naval base off in the distance at Point Sur. What they didn’t know was that the facility was part of a vast network of fully operational listening stations around the coastal United States, complete with government and civilian personnel to track and monitor Soviet submarines around the globe. Built in the 1950’s during the Cold War, this classified anti-submarine warfare facility was part of SOSUS, or the Sound Surveillance System.

SOSUS - Point Sur
SOSUS technician building – Point Sur, California. Photo by Manhattan Perry, March 2020.
NAVFAC civilian quarters, SOSUS technician building - Point Sur, California. USA. Photo by Manhattan Perry, March 2020.
NAVFAC civilian quarters, SOSUS – Point Sur, California. USA. Photo by Manhattan Perry, March 2020.

NAVFAC Point Sur was the official “cover name” given to the facility that was conducting “oceanographic scientific research” while secretly deciphering underwater sonic signatures from a hydrophone, or underwater microphone network that would accurately pinpoint the locations of the Soviet submarines. NAFAC Point Sur played a key role in identifying the location of the wrecked Soviet submarine – The K-129, which had relevance to a significant intelligence coup.

Before the introduction of SOSUS, anti-submarine warfare at the end of World War I and during WWII was very limited and rudimentary at best. With sonar detection at distances of only a couple thousand yards under favorable conditions, these early systems were only detecting high-frequency sounds at very short ranges. After extensive research of deep-ocean acoustics in the 1920’s and then the subsequent findings of incredible ranges and speeds of low-frequency sounds to travel incredibly long distances in certain temperatures and depths in the 19030’s and 40’s – the combination of this oceanographic research was the perfect storm for the SOSUS network of hydrophones to later pick up biological, ecological and mechanical (submarine) sounds from thousands of miles away.

From Undersea Warfare, official magazine of U.S. Submarine Force: “The first prototype of a full-size SOSUS installation – a 1,000-foot-long line array of 40 hydrophone elements in 240 fathoms of water – was deployed on the bottom off Eleuthera by a British cable layer in January 1952. After a series of successful detection trials with a U.S. submarine, the Navy decided by mid-year to install similar arrays along the entire U.S. East Coast – and then opted two years later to extend the system to the West Coast and Hawaii as well. These early SOSUS line arrays were positioned on the sea floor at locations that accessed the deep sound channel and oriented at right angles to the expected threat axis. Their individual hydrophone outputs were transmitted to shore processing stations called “Naval Facilities” – or NAVFACs – on multi-conductor armored cables.”

From Wikipedia: SOSUS is a multibillion-dollar network of hydrophone arrays mounted on the seafloor throughout the Atlantic and Pacific oceans. The SOSUS system takes advantage of the sound channel that exists in the ocean, which allows low-frequency sound to travel great distances.

The system’s first station came on line before there was any signature library of Soviet submarine acoustic characteristics while submerged. It was not until the Cuban Missile Crisis in 1962, when the quarantine reduced other shipping noises, that operators recognized unusual signatures that were confirmed to be Soviet snorkeling submarines. 

SOSUS Naval Facility Point Sur
SOSUS Naval Facility Point Sur, California, USA. Photo by Manhattan Perry, March 2020.

NAVFAC Point Sur was part of the Integrated Undersea Surveillance System (IUSS), a worldwide network of 30 defensive listening stations that tracked the movement of Soviet submarines. It provided continuous support to undersea surveillance. The personnel at the station were responsible for, among other things, to “support antisubmarine warfare command and tactical forces by detecting, classifying, and providing timely reporting” of Soviet submarines.To explain IUSS Naval Facility stations’ activities, an official cover story was written that described their mission of oceanographic surveys and research. Locally, the sign at the NAVFAC Point Sur entrance indicated the station was engaged in oceanographic research.

Although the US Navy was successful at keeping SOSUS operations a secret and detecting the locations of many Soviet and US submarines at long range for almost 15-20 years, the Walker-Whitman espionage and the end of the Cold War would eventually end the secrecy and need for the SOSUS spy network. The US Navy decided to allow this sonic detection system to be used by scientists with high ranking security clearances, in what was called “dual-use.”

Modern day SOSUS recordings of marine mammals and unidentified sounds

In present day, SOSUS is now used to study hydrothermal vents and pinpoint underwater volcanic eruptions. The system is also used to study the vocalizations of whales and other marine mammals, and measure ocean temperatures in relation to climate change.

Listen to the various sounds recorded in the oceanic depths from SOSUS, including humpback whale songs, blue whale songs and more in the video below.

With advancements in acoustic technology, radio frequency and computer software to track the data, the remaining operational SOSUS systems continue to explore the depths of the ocean for seismic and biological sounds. Along with qualitative and identifiable sounds, SOSUS and other microphone array systems record unexplainable sounds as well, like the mysterious “Bloop” and other unidentified sonic signatures.

Check out the sound of the “Bloop” recording in the featured video below.

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