The mystery of the 1997 underwater rumble solved by ice

Space · Published 29 October 2026 Swipe more like this →

In short: In 1997, scientists detected a powerful, ultra-low-frequency sound in the Pacific Ocean that sparked theories of giant sea creatures and secret military activity. For years, it remained an enigma of the deep, until researchers finally identified its source: a massive geological event in the Antarctic.

In 1997, American scientists first captured the acoustic phenomenon known as "the Bloop." The U.S. National Oceanic and Atmospheric Administration (NOAA). To track submarine volcanic events, the group deployed specialized underwater microphones spanning over 3,219 kilometres of Pacific waters. The noise was noted for being extremely loud and possessing a unique characteristic that distinguished it from any other sounds they had previously documented.

Because approximately 95 percent of the ocean remains unexplored, the unknown origin of the Bloop led to a wide array of speculations. Theories ranged from human-made sources, such as ship engines, fishing boat winches, or secret military exercises, to biological possibilities involving whales, giant squids, or entirely unknown sea creatures. These mysteries persisted for years as the Pacific Marine Environmental Laboratory (PMEL) continued to deploy hydrophones closer to the Antarctic to better understand the global ocean acoustics environment.

The mystery was finally solved in 2005. Scientists determined that the Bloop was actually an icequake. This occurs when an iceberg cracks and breaks away from an Antarctic glacier. As global warming progresses, these icequakes occur more frequently, causing glaciers to crack and eventually melt into the ocean. Interestingly, the term "bloop" itself is a back-formation from the word "blooper," which first appeared in 1941.

This discovery highlights the importance of long-term acoustic monitoring. PMEL’s Acoustics Program uses these unique tools to gather data sets that help identify and assess the impacts of both natural processes, like icequakes and volcanoes, and human activities on the marine environment. It serves as a reminder that even the most mysterious sounds of the deep can often be explained by the powerful, natural movements of our planet's ice and water.

General information, not professional advice. Spotted an error? Flag the card or see corrections and complaints.

Intellect Plus is a visual educational discovery platform for exploring fascinating facts and ideas. Brain Food, Not Brain Rot. What is Intellect Plus?

Related

• The ocean floor isn't always where your sonar says it is
• How a steel ball and a telephone line first revealed the deep ocean's secrets
• The secret underwater 'ears' that listened for Soviet submarines
• How a Swiss-designed bathyscaphe reached the deepest point on Earth in 1960
• Underwater sound travels four times faster than it does in air
• Why your fortune cookie feels like a personal message from destiny
• The end of the dinosaurs was not the end of giants
• The sudden appearance of 35 major animal phyla in just one era
• Satellites are currently watching a new island potentially rise from the Bismarck Sea
• Could green ammonia clean up the world's dirtiest ships?
• Wealth is not about what you have but how you think
• How Joe Rothenberg led the mission to save the Hubble Space Telescope

More in Space · Latest · A–Z · All topics