No. 003 FRI 02 OCT 2026

The ocean’s most famous mystery sound was ice breaking apart.

The Bloop — Southern Ocean

In the summer of 1997, NOAA’s underwater microphones recorded a loud, rising sound that became known as the Bloop. For years it was one of the ocean’s best-known unexplained noises. Later recordings settled it: the Bloop matches icequakes — the sound of huge Antarctic icebergs cracking and fracturing, loud enough to be detected more than 5,000 kilometres away.

Why it’s interesting

Fig. 003 Frequency over time, as a hydrophone hears it. One event rises out of the background.

The longer version

NOAA hydrophones in the Scotia Sea later picked up numerous icequakes with spectrograms very similar to the Bloop, and the team used them to track the iceberg A53a as it disintegrated near South Georgia Island in 2008.

Based on the direction the original sound arrived from, the iceberg or icebergs that produced the Bloop were most likely somewhere between the Bransfield Strait and the Ross Sea, or near Cape Adare.

The ocean’s most famous mystery sound was ice breaking apart.

Why it’s interesting

The longer version

See how we got here

Sources