The Bloop
In 1997, underwater microphones thousands of kilometres apart picked up a deep, rising sound from the remote South Pacific.
What was reported
In the summer of 1997, a network of underwater microphones used by the US National Oceanic and Atmospheric Administration (NOAA) recorded a powerful, very low sound that rose in pitch. It was picked up by sensors more than 5,000 km apart, which made it one of the loudest underwater sounds ever recorded.
Because it rose in pitch like some animal calls, it was quickly suggested that it came from a creature far bigger than any whale. The 'Bloop' became a favourite of ocean-monster stories.
Explanations offered
NOAA later concluded that the sound matched an icequake: a large iceberg cracking and breaking away from Antarctica. Similar sounds have since been recorded from icebergs.
- When
- 1997
- Where
- South Pacific Ocean, west of the tip of South America
- Witnesses
- Underwater microphones run by the US government
- Status
- Explained
Famous cases are real, widely reported events. Each file sets out what witnesses said and the explanations that have been offered, without taking a side.