Underwater Sounds: Beyond the Bloop

Underwater Sounds

Underwater sounds are very common. In fact, the ocean can be a pretty noisy place when you factor in all the human activities, weather, geophysical events, and animal sounds that can be detected virtually everywhere. Scientists have tools to monitor such noises, but sometimes, they encounter unknown underwater sounds.

If you’re a fan of conspiracy theories or weird natural anomalies, you might have heard whispers of “the Bloop” before. We’re going to talk about this, and some other strange underwater noises. And we’ll take a look at some of the crazy theories people have come up to explain them.

We can hear the call of Cthulhu now…

Underwater Sounds

The Bloop

We heard the Bloop in 1997 poking around for volcanoes near the South American coast. If you want to see the exact latitude and longitude of the Bloop, here you go.

Further Reading: What’s the Difference Between Latitude and Longitude?

Anyway, when the Bloop went off, the microphones NOAA shoved underwater picked it up from over 3,000 miles away (4,800 kilometers) from the source. At the end of the day, that makes the Bloop the loudest noise we’ve ever heard from deep within the ocean depths. 

Also here’s the NOAA released audio of the Bloop.

Solving the Mystery

The Bloop was actually solved by accident. About a decade after we heard it no less (2005). NOAA’s Pacific Marine Environmental Laboratory (PMEL) was locked onto discovering the Bloop’s origins, plopping microphones all over the ocean deep. These microphones were largely to do research on deep sea volcanoes or earthquakes. 

While listening, PMEL picked up sounds with the Bloop’s signatures. Turns out, the Bloop was just an icequake–a large iceberg breaking off from a larger glacier.

The long short; we solved the Bloop mystery thanks to global warming causing more frequent icequakes. Nice? 

For a more in-depth look at the Bloop, check out: The Bloop – An Underwater Mystery

Theories About Underwater Sounds

But, what happened from 1997 and the years following the Bloop? Well, given that the vast majority of the Earth’s oceans are unmapped (something over 80%, or even 90%), people unsurprisingly took theories regarding the Bloop and ran with it. Things that might instill existential and cosmic levels of terror. 

Honestly, the fact that we don’t know most of what’s in our own oceans is enough existential terror on its own.

Trivia Fact: More people have walked on the Moon than visited the bottom of the Mariana Trench, the deepest part of the ocean.

Anyway, theories that we’d found some kind of undersea god-monster went wild when NOAA confirmed that the Bloop was not something we human underlings could have produced. They even threw open the floodgates by saying it was “possibly biological.”

Of course that came with a huge asterisk, with representatives trying to make clear that a biological origin was just a possibility someone threw at a wall since we had absolutely no idea what the Bloop was.


Before we get really wild with Bloop theories, many gravitated towards something more easily grasped. Ergo, the Bloop was largely attributed to a really big pod of whales. Unfortunately, whales simply are not loud enough to produce a noise like the Bloop, and a group of whales isn’t going to realistically be big enough to make the noises we want. 

Alright, fine. Since NOAA did tell us tinfoil hat enthusiasts that the Bloop was possibly biological, it’s time to add megalodon into the ring. That, and a bunch of other old, ancient creatures that were super big as a product of their time. 

While it could have been an animal, it was largely agreed upon that no animal we know of would be able to make a low-frequency sound as loud as the Bloop.

Luckily, our theory crafting friends had a pretty neat card up their sleeve. 

The Call of Cthulhu

If you’re a fan of cosmic horror, you’ve likely heard of (or maybe read) H.P. Lovecraft’s work. Either that or you only know he did the big squid monster (Cthulhu) and that Lovecraft was extraordinarily racist. Seriously, even contemporary authors of his time (the early 1900s) thought he was on the far end of racism. 

Lovecraft’s Cthulhu mythos, as you might imagine, outlines a lot of the ins and outs of Cthulhu. Well, as much of Cthulhu one could outline while still remaining on-theme for cosmic horror.

In that mythos, Cthulhu is known as a Great Old One. Basically one of a pseudo-pantheon of really, really ancient beings residing on Earth, sleeping. Cthulhu specifically makes its deep slumber in the ocean depths, probably somewhere in the 90% of unexplored ocean. Anyway, point is that Cthulhu is an agreed upon malevolent being whose age would be like comprehending infinity. 

Further Reading: What Is Cosmic Horror?

Cthulhu Takes a Nap

Before his slumber, Cthulhu made house on the island R’lyeh. It’s quite literally described as a “corpse-island” and it’s a fun mess of non-Euclidean geometry. Somewhere in there, Cthulhu is entombed and it dreams–probably of some not great things. Just keep in mind that Cthulhu controls minds and has cults dedicated its summoning.

In Lovecraft’s writing, Cthulhu and his tomb-island-prison actually have an outlined latitudinal and longitudinal location. A location that happened to be about 900 miles  (1,500 kilometers) from the Bloop’s triangulated position. In the grand scheme of “this being is so far beyond human understanding looking into its eyes would drive you insane,” a trifling 900 miles is like saying Cthulhu was napping right on top of the Bloop!

So Cthulhu was one of the big potential Bloop culprits, calling out to its followers to wreak all kinds of shenanigans on us puny fleshlings.

But Wait… More Underwater Mysteries!

NOAA still has two mystery sounds, the 1991 Upsweep and the 1997 Whistle. The Whistle is a little less exciting, sounding a lot like deep sea volcanic noises. Though those noises can typically have their positions triangulated as three hydrophones pick up the same noise. Strangely, only one picked up the Whistle, making its position impossible to lock down. Still probably just a volcano though.

Upsweep is a little more interesting, coming in and out with the seasons–peaking in spring and fall times. We still don’t have a hard location, but the noise is near seismically active regions. Might just be more volcanoes, but seasonal shenanigans are fun! 

At the end of the day, the Bloop was just a product of increasingly aggressive climate change. So maybe there is some existential terror there after all.

Know your oceans? See if you do here.