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Unexplained Sounds Coming From The Ocean

Unexplained Sounds Coming From The Ocean 3

Several very unusual  sounds coming from the oceans have been recorded by scientists world-wide.

Are the sounds caused  by very large life forms lurking in the unexplored darkness of Earth’s deep oceans or perhaps something else?

Something is down there and experts do not know what it is…

All of these sounds have no thing in common – they remain unexplained.


In 1997, deep sea microphones captured a loud and unusual sound, dubbed a Bloop in Earth’s Pacific ocean.

Although Bloops are some of the loudest sounds of any type ever recorded in Earth’s oceans, their origin remains unknown.  The Bloop sound was placed as occurring several times off the southern coast of South America and was audible 5,000 kilometers away.

The sound does have similarities to those vocalized by living organisms, but researchers say not even a blue whale is large  enough to croon this loud. In fact, no known creature on Earth can create this sound, scientists say.

“The sound waves are almost like voice prints. You’re able to look at the characteristics of the sound and say: ‘There’s a blue whale, there’s a fin whale, there’s a boat, there’s a humpback whale  and here comes and earthquake, Christopher Fox of the U.S. National Oceanic and Atmospheric Administration’s Acoustic Monitoring Project at Portland, Oregon said.But the Bloop is a mystery. Is it a monster of the deep?

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No further Bloops have been heard since 1997, although other loud and unexplained sounds have been recorded in other places under different circumstances.

Listen to the Bloop sound

Other examples of unexplained sounds coming from the oceans are:


The sound was recorded on March 1, 1999 on the Equatorial Pacific Ocean autonomous hydrophone array.

The source of the sound is unknown, but is sufficiently loud to be heard over the entire array. The duration is approximately 15 seconds and  is severely band limited. The approximate origin is 1999JD60 2218Z near 15S, 98W. Listen to the Julia sound


This sound was recorded on March 5, 1997 on the Equatorial Pacific Ocean autonomous hydrophone array.

The sound rises to a quasi-steady frequency. The origin of the sound is unknown.  Listen to the Train sound

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Slow Down

This sound was recorded May 19, 1997 on the Equatorial Pacific Ocean autonomous hydrophone array.

The sound slowly descends in frequency over about 7 minutes and was of sufficient amplitude to be heard on three sensors at 95W, and 8S, 0, and 8N,  at a range of nearly 2,000 km. This type of signal has not been heard before or since. It yields a general location near 15oS; 115oW.

The origin of the sound is unknown.   Listen to the Slow Down sound


This sound was recorded by the autonomous hydrophone deployed at 8oN, 110oW on July 7, 1997 at 0730Z.

Origin of the signal is unknown, and it was not detected on any other hydrophone. The band of energy between 1 and 6 Hz represents “strumming” of  the mooring in mid-water currents. Listen to the Whistle sound


This sound was present when PMEL began recording SOSUS in August, 1991.

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It consists of a long train of narrow-band upsweeping sounds of several seconds duration each. The source level is high enough to be recorded  throughout the Pacific. It appears to be seasonal, generally reaching peaks in spring and fall, but it is unclear whether this is due to changes  in the source or seasonal changes in the propagation environment. The source can be roughly located at 54o S, 140oW, near the location of  inferred volcanic seismicity, but the origin of the sound is unresolved. The overall source level has been declining since 1991 but  the sounds can still be detected on NOAA’s  equatorial autonomous hydrophone arrays.   Listen to the Upsweep sound

What are these mysterious and unexplained sounds?

According to scientists, some of the sounds can have straightforward origins and they can be traced to weather and ocean currents.

The upsweep sound was first believed to be biological, possibly produced by fin whales. However, when the sound was picked up by receivers on opposite  sides of the Pacific, researchers concluded that it was too loud to have been produced by a whale. The signals also stayed the same over the course of  many seasons, whereas whale song should have varied as the whales migrated. Also, the sound was too uniform to have come from whales.

Although Upsweep’s relatively pure tone didn’t fit with the more varied sounds typical of other volcanic activity, the researchers speculated that it  came from some kind of oscillation of bubbly liquid, perhaps seawater coming into contact with a large pool of lava. “Somehow within the volcanic cycle,”  explains Emile Okal of Northwestern University in Chicago, “there must be some resonance of a column of water or gas.”

Unexplained Sounds Coming From The Ocean 4
Our oceans still hold many secrets left to unravel.
The train sound that resembles the rushing noise of a distant train could be ocean currents.

“Moving fluids generate vibrations,  just like blowing air through a clarinet,” Fox says. “If you have moving ocean water and the right conditions coming around a seamount  or something, that could generate sound.”

Scientists believe that the Bloop  sound most likely comes from some sort of animal, because its signature is a rapid variation in  frequency similar to that of sounds known to be made by marine beasts. It could be a giant squid, but then again we have little  information on these creatures. “We don’t have a clue whether they make noise or not,” says Fox.

Perhaps the most tantalizing sound is Slowdown, which has been picked up a few times every year since about May 1997.

“It sounds like an airplane going by,” says Fox. It has been detected in the Atlantic as well as the Pacific, but always from the  south, indicating an Antarctic origin.

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Could the sound come from a moving iceberg? We simply don’t know. What we do know is that 75 % of the earth is covered with water.  97 % of earth’s water is in the oceans.

Now, don’t forget that we have only explored 5% of all our oceans. We really do not know what is down there….

Much remains to be learned from exploring the mysteries of the deep.


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