IN THE summer of 1997, an array of underwater microphones, or hydrophones, owned by the US government picked up a strange sound. For a minute, it rose rapidly in frequency; then it disappeared.

Does the bloop still exist?

Dziak explained to us the NOAA's findings, and confirmed that "the frequency and time-duration characteristics of the Bloop signal are consistent, and essentially identical, to icequake signals we have recorded off Antarctica".

How old is the Bloop?

The source of a mysterious rumble recorded in the ocean in 1997 is now known to have originated from an icequake. "The Bloop" is the given name of a mysterious underwater sound recorded in the 90s.