What was 'The Bloop'?

In the summer of 1997, the US National Oceanic and Atmospheric Administration (NOAA) recorded an extremely loud, minute-long sound some 1,500 miles off the coast of Chile. The unknown sound was picked up by underwater hydrophones some 1,800 miles apart, making it the loudest unidentified underwater sound ever recorded, and it didn't match with any man-made or known deep-sea animal source.

Nicknamed ‘the Bloop’, this mysterious sound was never heard again, becoming a curiosity for scientists and a springboard for wide-ranging theories for the general public for many years to come. However, following surveys conducted between 2005 and 2010, NOAA scientists determined that the sound was consistent with the rupture of a massive Antarctic ice sheet. In this short documentary from the US director Cara Cusumano, the retired NOAA oceanographer Christopher Fox recalls his experience with ‘the Bloop’, including how it went from a scientific concern to a rare science story that captured the public imagination.

There's some nice comments near the end about how, while speculation about 'the Bloop' went "beyond scientific rigour", Fox wasn't bothered by it, and ultimately he is "glad there's still some mysteries out there".