The ocean’s celebrity mystery noise was ice cracking.

The part that checks out ↘

It really happened.

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.

A sound that seemed to demand a creature described something larger: an iceberg coming apart, audible across an ocean. The mystery was solved by listening longer.