The Bloop—a low‑frequency, high‑amplitude sound—was recorded by NOAA’s hydrophones in the Pacific Ocean in 1997, reaching listeners over 3,000 miles (4,828 km) away.
For years, scientists and ocean enthusiasts speculated that the eerie rumble could have been produced by an enormous marine creature—perhaps a giant squid, a creature larger than a blue whale, or even an iceberg cracking under pressure.
The Bloop was an extraordinarily powerful underwater noise that travelled vast distances. NOAA’s instruments detected it in the ultra‑low‑frequency band that is typical of marine mammals, yet its amplitude far exceeded that of any known animal.
Analysis of the sound’s spectral content and its travel path led NOAA researchers to conclude that the source was an Antarctic glacier. The data are consistent with ice quakes—cracking and breaking ice—that generate intense acoustic energy.
These conclusions were reached after a comprehensive review of recordings from a global network of hydrophones that were originally deployed to monitor submarine activity. Instead of detecting vessels, the network uncovered one of the loudest natural ocean sounds ever recorded.
If the Bloop had come from an animal, it would have had to be larger than any blue whale ever measured. While deep‑sea species such as the giant squid thrive in extreme depths, no known organism can produce a sound of the Bloop’s magnitude. Yet, because humans have explored only about 5 % of the ocean, the possibility of an undiscovered creature remains an intriguing hypothesis.
Although the Bloop is now attributed to ice quakes rather than a living creature, its detection has implications for our understanding of a warming world. As Antarctica’s ice shelves retreat, the frequency of ice cracking events—and the accompanying acoustic signatures—may increase, providing a new tool for monitoring climate change.
This article was written with the assistance of AI technology and was subsequently fact‑checked and edited by a HowStuffWorks editor.
