At the height of the Cold War tension between the United States and the Soviet Union, the

American Navy was using audio technology to detect Soviet submarines.

These high-powered underwater microphones could detect unusual sounds from hundreds, even

thousands of miles away, helping the military see far into the depths of the ocean.

After the Cold War ended, the National Oceanic and Atmospheric Administration, otherwise known

as NOAA, built on that old microphone system with the hope of gaining a new understanding

of the massive unexplored world beneath the ocean waves.

They studied ambient sounds, geophysical noise, and bioacoustics, the sounds that ocean

creatures make.

But in 1997, they encountered a sound that defied explanation, a very low frequency, very

organic, and very powerful sound, so powerful that it was picked up by their microphone system

from over 3,000 miles away.

Oh, and HP Lovecraft fans might get a kick out of the location they pinpointed.

This roughly 900 miles from the location of the mythical island city of Rulaya, where

Kathulu is imprisoned, waiting and dreaming.

It didn't help that, at the time, NOAA deemed this sound to be neither man-made nor geological.

It seemed to be organic, with a signal that varied too much to be mechanical.

Today scientists lean toward another theory though.

It's the sound of icebergs scraping against the ocean floor.

Maybe.

Many people still wonder what the bloop, as they called it, really was.

We wonder because there's something dark and mysterious about the ocean.

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