BATHYS — North Atlantic deployment

Office of Subsea Operations

Monitoring of deep-ocean anomalies, thermal event tracking, and subsea acoustic surveillance across six North Atlantic deployment zones.

The Office of Subsea Operations, designated BATHYS, was established in 1891 following the Institution’s analysis of reports from the HMS Challenger deep-sea expedition of 1872–1876. The Challenger’s crew had documented acoustic phenomena at depth that the Institution’s analysis suggested were inconsistent with any known geological or biological source.

BATHYS currently maintains six passive monitoring arrays in the North Atlantic at depths between 2,000 and 4,800 metres. The arrays monitor acoustic signatures, thermal gradients, and electromagnetic anomalies. Data is transmitted to the Appleby archive on a continuous basis.

Current Operations

All six Atlantic arrays are operational. Array 4 (North Atlantic Ridge sector, 47°N) reported an anomalous acoustic signature in the period July–September 2019 that has not been classified. The signature does not match any known geological, biological, or anthropogenic source in the Institution’s reference library. Monitoring of Array 4 has been elevated to continuous active review.

The 1908 Event

In June 1908, Array Precursor Station 2 — then a tethered instrument package rather than a fixed array — recorded a pressure event inconsistent with the Tunguska airburst occurring simultaneously in Siberia. The Institution’s assessment, filed in Archive record BA-1908-001, notes that the event registered at depth before the Tunguska event’s seismic signature arrived. The assessment is available to Fellows of the Third Degree.