What Caused the Loudest Underwater Sound Ever Recorded?

By Rose Pastore on at

In 1997, scientists with the U.S. National Oceanic and Atmospheric Association were recording the sounds of underwater volcanic activity when they picked up a noise that was so incredibly loud—louder than any underwater sound ever detected—that they initially thought it must be an equipment malfunction. But then another underwater microphone picked up the same noise... over 3,000 kilometres away.

What could have created such a sound? No living animal—at least, no known creature—could have produced it. The U.S. Navy denied any doing testing in the area. When a sped-up recording of the sound went public, it soon became known as “the bloop,” and conspiracy theories abounded. Years later, scientists finally did discover the true nature of the massive noise. In the second episode of our new series “Sound Mysteries,” we look into the case of the mysterious underwater bloop.


“Sound Mysteries” is a new Gizmodo series in which we explore weird or unexplained sonic phenomena.