Mysterious underwater sounds

The Bloop
The “Bloop” sound is a mysterious and intriguing underwater sound that was detected by the U.S. NOAA in 1997. It was recorded by hydrophones in the Pacific Ocean and captured around 4828 km away. The sound had unique characteristics, resembling a deep and low-frequency sound, similar to the vocalizations of whales, but much louder than the loudest animal in the world – the blue whale. 

There were a few speculations: from secret military experiments to massive undiscovered sea creatures. However, after further investigation by NOAA scientists it turned out that the sound was likely produced by the movement of massive icebergs in Antarctica.

As glaciers move and crack, they release tremendous amounts of energy, creating sounds that can travel long distances underwater. The “Bloop” was consistent with the acoustic signature of ice-related phenomena. Large icebergs as they break apart, generate powerful underwater acoustic signals.

The “Bloop” sound remains one of the most famous examples of natural phenomena initially misunderstood as something more exotic.

The Upsweep
Like the “Bloop,” it was considered as discovery due to its mysterious nature. The “Upsweep” is characterized by a series of narrowband upsweeping sounds, which have a distinctive rising and falling pitch, resembling the sound of a large, slow-moving wave. The source of the “Upsweep” remained unidentified for many years.

In early 2000s, the “Unsweep” sound was associated with volcanic eruption nearby Pacific Ring of Fire. The sound is thought to be caused by the release of gas and fluids from volcanic vents on the ocean floor. These vents emit a continuous stream of bubbles, which can create distinctive acoustic signatures as they rise through the water column.


There was a lot of speculation about the source of the “Julia” sound, ranging from submarine movements to secret military operations.

Researchers eventually concluded that the “Julia” sound is likely associated with the movement of icebergs or large chunks of ice scraping along the ocean floor. When these massive pieces of ice encounter irregularities or obstacles on the seafloor, they can produce distinctive acoustic signals as they grind against the ocean floor.

The rhythmic, pulsating nature of the “Julia” sound suggests a regular and repeating process. While the exact mechanisms behind the “Julia” sound are still not fully understood, its association with ice-related phenomena provides a plausible explanation for its origin.



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