This Is What Actually Caused That Underwater “Bloop” Sound

The Bloop was one of the biggest mysteries to plague the world since it was first heard in 1997. It’s a sound that’s been the subject of countless conspiracy theories revolving around Cthulhu-like monsters and catastrophic activity within Earth’s core, but the truth is far simpler than anything we could imagine.

So, how’d one noise go from “possibly biological” and “sea monster lurking in the ocean,” to all the way down to “no big deal”? As it turns out, scientists actually had it figured out the whole time.

What is the Bloop?

For anyone who doesn’t know, the Bloop was a single sound captured by two separate underwater listening stations that were located around 3,000 miles apart in the Pacific Ocean. At the time, scientists couldn’t explain what the noise was, other than the fact it was exceptionally loud, and they referred to it as “the Bloop.” In fact, it’s one of the loudest noises that’s ever been recorded underwater, and researchers knew it was special from the moment they heard it.

“It’s unusual when a sound is recorded on all of the sensors we have deployed,” said National Oceanic and Atmospheric Administration (NOAA) seismologist and acoustics program manager Bob Dziak. “If it’s a ship, or a whale, when it makes a sound in the ocean, it isn’t big enough to be recorded all the way across the Pacific. But this sound was recorded on many hydrophones so it stood out in our mind as being something unique.”

So, what was it?

We hate to be the ones to deliver the anticlimactic news, but it didn’t come from a giant whale or deep sea-dwelling tentacle monster—it was an ice shelf moving.

In an interview with WIRED, Dziak explained that the sound is actually pretty similar to others that have been recorded over time. “The frequency and time-duration characteristics of the Bloop signal are consistent, and essentially identical, to icequake signals we have recorded off Antarctica,” he said.

He went on to explain that in 2005, NOAA scientists set up a survey in the Drake Passage and the Bransfield Strait, both of which are in Antarctica. They continued to record until 2010 and, when they eventually analyzed the data they had captured, they determined that the majority of natural sounds heard in the southern ocean is that of ice cracking and breaking apart.

“Each year there are tens of thousands of what we call ‘icequakes’ created by the cracking and melting of sea ice and ice calving off glaciers into the ocean, and these signals are very similar in character to the Bloop,” Dziak said.

Wait a minute—how does cracking ice end up sounding like that?

Anyone who’s ever heard the Bloop knows how easy it is to assume it came from a living creature—it sounds pretty much identical to a call you’d hear from a giant whale. However, Dziak said that scientists themselves were never seriously considering that the sound came from something living. Rather, people heard that the sound was “possibly biological” and let their imaginations run wild. It also doesn’t help that the recording most people have heard of the Bloop isn’t what it actually sounded like.

“What has led to a lot of the misperception of the animal origin sound of the Bloop is how the sound is played back,” Dziak explained. “Typically, it is played at 16 times normal speed, which makes it sounds like an animal vocalisation of some sort. However, when the sound is played in real-time it has more of a ‘quake’ sound to it, similar to thunder.”

The location the Bloop came from didn’t help, either.

To help fuel the fires of the rumor that the sound was produced by an underwater beast, fans of the H.P. Lovecraft short story The Call of Cthulhu determined that the Bloop came from a point fairly close to where the underwater city known as R’lyeh can be found. This is said to be the spot where Cthulhu is imprisoned, so you can imagine how excited fans of the story were to hear about this. Others, however, were convinced the sound came from a giant squid, a theory that even scientists considered, according to Dziak.

This is said to be the spot where Cthulhu is imprisoned, so you can imagine how excited fans of the story were to hear about this. Others, however, were convinced the sound came from a giant squid, a theory that even scientists considered, according to Dziak.

Even the thought that it was from some creature we’ve never heard of seemed pretty feasible. After all, according to the NOAA, we have yet to explore approximately 95 percent of the ocean area that covers our planet. As recently as 2012, scientists even caught a glimpse of a rare spade-toothed beaked whale—and one of its calfs, too—after it washed up along a New Zealand beach. Prior to that, no living human had even seen one before—all we had were three partial skulls that had been collected over a century and a half. We didn’t even capture footage of giant squids until 2004, and it was only one animal. Clearly, there’s a lot out there we don’t yet know about.

Prior to that, no living human had even seen one before—all we had were three partial skulls that had been collected over a century and a half. We didn’t even capture footage of giant squids until 2004, and it was only one animal. Clearly, there’s a lot out there we don’t yet know about.

There was one Bloop-like noise with an animal origin.

In 2014, multiple sounds were recorded from within the deepest part of the ocean, the Mariana Trench, which lies between Australia and Japan. Each sound lasted for no more than 3.5 seconds and consisted of around five parts. They also got as low as 38 hertz and finished off with a metallic-sounding finish that sometimes came in at 8,000 hertz.

The sound, which is referred to as Western Pacific Biotwang, was thought to be the mating call from either baleen or dwarf minke whales, but researchers still have their doubts because the sounds seem to come year-round.

Until they figure it out, let’s blame it on Cthulhu and stop letting science ruin our fun.