Extremely powerful sound that couldn't be made by animals was recorded from the deep sea

A sound that was picked up in the depths of the ocean puzzled experts for years, before it was finally revealed what was behind the mystery.

And spoiler alert, it wasn't a deep sea monster.

The vastness of the ocean continues to fascinate many, and with only around 0.001 percent of the deep seafloor having been explored (according to a new study), there's no doubt that there's so much going on under the waves that we aren't even aware of.

From mysterious sea creatures being washed up on beaches, to the bizarre discovery of 'hoof prints' on the ocean floor, the secrecy of the ocean is constantly leaving us with unanswered questions and, of course, fuelling the conspiracy theorist's wild claims about what's really down there.

Well, these theorists will be disappointed after experts were able to solve the mystery of a sound that was detected back in 1997.

There's an awful lot going on down on the ocean floor... and with that comes a lot of strange sounds (Getty Stock Image)

Researchers at the National Oceanic and Atmospheric Administration (NOAA) were listening for underwater volcanic activity in the southern Pacific when they recorded a 'strange, powerful, and extremely loud' sound.

The hydrophones (underwater microphones) that were placed more than 3,219 kilometres apart across the Pacific recorded the noise several times, and it wasn't anything like the researchers had heard before.

As well as being loud, it had a unique characteristic... thus birthing it's name, the Bloop.

Because of the mystery surrounding the Bloop, scientists from NOAA’s Pacific Marine Environmental Laboratory (PMEL) got to work to try and discover its origin.

The possibilities were endless: Was the Bloop made from secret underwater military exercises? Ship engines? Fishing boat winches? Or what about marine life like giant squids, whales, or even a sea creature unknown to science... Loch Ness Monster, I'm looking at you.

Researchers were puzzled by 'the Bloop' for quite some time (Getty Stock Image)

But scientists very soon ruled out that it wasn't possible for an animal to be behind the noise, and as the years passed, they finally stumbled upon their answer.

This happened by chance in 2005 when PMEL researchers deployed hydrophones closer to Antarctica in an ongoing effort to study the sounds of sea floor volcanoes and earthquakes.

After picking up the thunderous rumbles that the Bloop was unique in making, researchers came to the realisation that it was simply the sound of an icequake - an iceberg cracking and breaking away from an Antarctic glacier.

Icequakes are becoming more common due to global warming, the NOAA explains, so the Bloop is likely a sound that's being detected more frequently.

NOAA and Oregon State University seismologist Robert Dziak spoke to Wired.co.uk about the identification of the Bloop and how it was realised early on it wasn't made from an animal.

It turns out the Bloop was simply the sound of an icequake, which is common in regions like Antarctica (Michel Setboun/Getty Images)

"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 explained.

That is what made it 'extremely unlikely' that the sound was animal in origin, but he also pointed out that the theory that the Bloop was caused by an animal wasn't ever really a serious one.

"What has led to a lot of the misperception of the animal origin sound of the Bloop is how the sound is played back," he added.

"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."

So, that puts to bed yet another sea monster theory...