Concerning reason the world's deepest hole had to be sealed up

Russia is home to the world's deepest hole.

The Kola Superdeep Borehole is entirely manmade, measuring 40,230 feet deep in the Arctic Circle.

It took a whole 20 years to drill this mammoth hole, earning its ominous nickname of "the entrance to hell."

Perhaps, because locals claim to hear the screams of souls tortured in hell coming from the hole in northwestern Russia.

To illustrate its depth, the hole's depth is equal to the combined height of both Mount Everest in Nepal and Japan’s Mount Fuji, around 12.2 km or 7.58 miles.

However, despite its depth, the hole only penetrates about a third of the Earth's crust, with temperatures already as high as 180 degrees Celsius (356 Fahrenheit).

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Uli Harms of the International Continental Scientific Drilling Program, reflected on his time as a young scientist working on the Kola borehole's German rival.

"When the Russians started to drill they claimed they had found free water - and that was simply not believed by most scientists," he said.

"There used to be common understanding among Western scientists that the crust was so dense 5km down that water could not permeate through it.”

The US started the project in 1950 with a plan to get as deep as the Earth's mantle, with the Soviets and Germans following suit in 1970 and 1990, respectively.

However, the Kola borehole project has since been sealed off for various reasons, including safety violations, environmental concerns and financial constraints. No chance of falling in now!

The hole was dug with vertical drilling systems to maintain a straight path with minimal chance of bends.

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But, in the final stretch, the hole deviated 200 metres from its vertical path and getting the necessary equipment caused several delays to the expedition.

Ultimately, the project failed to reach the desired depth of 10 km within the given time, according to Harms.

Drilling ceased in 1992 when temperatures were reported to be twice as expected. This meant that the drilling equipment could not cope with the heat, requiring further costs and tools and of course, delays.

Furthermore, the extremely high costs of the repeated expeditions made it difficult to continue working regularly.

Eventually, after the collapse of the Soviet Union, there was no money to fund such ambitious projects, and the facility officially closed in 1995.

The desolate site now attracts adventurous tourists who wish to see the remnants of this unique project.