It’s not hard to spot either, as around the rim of the hole a little bit of land rises up above the waters of the Caribbean Sea and to peer into it is to look into a cylinder of deepest blue.

Speaking of deep, the Great Blue Hole is around 400ft deep, which is why getting to the bottom proved tricky for a long time.

It’s not the only ‘blue hole’ in the world but this one is truly gargantuan in proportions.

Made famous by the explorer Jacques Cousteau, years later his grandson Fabien would venture down into the hole alongside Virgin billionaire Richard Branson.

In 2018 a pair of submarines dove down into the hole to explore it and at around 300ft beneath the surface they found a layer of hydrogen sulphide, and below that the water was dark and devoid of life.

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Still not at the bottom, the expedition delved further until they made it down to the base of the hole, where they made a discovery that was disturbing for a few reasons.

Lying at the bottom of the Great Blue Hole was, of course, some rubbish.

The team found a two-litre plastic bottle, as well as a long-lost GoPro with some photos of someone’s holiday on it.

But that wasn’t all.

The team also discovered two bodies in the hole; divers who had gone missing in the great cavern.

Though the sight definitely would have been unnerving, the team decided to leave the bodies where they were, determining the hole to be a good final resting place.

However, they did let the Belize government know the divers had been found.

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The shocking discoveries didn’t end there, as when the crew dove in a submersible vehicle into the depths of the hole, they found a large series of caves which were home to hanging stalactites – but scientists didn’t think it was possible for stalactites to form beneath the surface of the water.

The revelation indicated that the caves, located hundreds of feet beneath the surface of the ocean, were once on dry land.

Branson highlighted how disturbing this discovery is for the state of the planet in a post on Virgin.com, writing: “The Blue Hole is made of a complex system of caves that once formed on dry land. It is proof of how oceans can rise quickly and catastrophically.

“Sea levels were once hundreds of feet lower. 10,000 years ago the sea level rose by about 300 feet when a lot of ice melted around the world. At 300 feet down you could see the change in the rock where it used to be land and turned into sea.”

Branson described the scene as ‘one of the starkest reminders of the danger of climate change [he’s] ever seen’.