The SOSUS mission is declassified
The mission of the US Navy Sound Surveillance System, a network of seafloor hydrophone arrays built from the mid-1950s across the Atlantic and Pacific, is declassified. Its use of the deep sound channel, designed to hear submarines at long range, turns out to suit low-frequency baleen whale calls exactly. A military listening system becomes, without being redesigned, the first basin-scale whale observatory.
Historical — it happened, and the record is settled.
Subjects
- Passive Acoustic Monitoring Arrays · technology system · Global ocean basins · not located
Evidence
Partly verified — Core facts are sourced; some optional detail is deliberately absent.
SOSUS and its reuse for whale acoustics, including the 52 Hz call
SOSUS was installed by the US Navy from the mid-1950s as a network of seafloor hydrophone arrays across the Atlantic and Pacific, exploiting the deep sound channel so that low-frequency sound travels great distances; its mission was declassified in 1991. The 52 Hz call was first identified in 1989 by William Watkins of the Woods Hole Oceanographic Institution from Navy hydrophone data, and the same call was tracked seasonally across the North Pacific over hundreds to thousands of kilometres between recordings. V55 verification basis: retrieved in search summary; neither the Watkins publication nor a Navy declassification record was consulted.
Discovery of Sound in the Sea (University of Rhode Island); with the MIT Press Reader account of the SOSUS whale observatory · accessed 2026-08-08 · Partly verified
https://dosits.org/galleries/technology-gallery/locating-objects-by-listening-to-their-sounds/sound-surveillance-system-sosus/ ; https://thereader.mitpress.mit.edu/the-cold-wars-accidental-whale-observatory/
Recorded on Passive Acoustic Monitoring Arrays
- The 52 Hz call is identified in Navy hydrophone data
- The SOSUS mission is declassified
- Blue whales are found back at South Georgia
Related
Related because they share a subject in the Atlas — never because the text looks similar.