The deepest hole ever dug went 7.6 miles down until scientists heard a 'terrifying sound'

The record-breaking hole bores down more than 40,000 feet and was allegedly dubbed by locals the "Well to Hell" because of a mysterious noise.

By Richard Ashmore, Senior News Reporter

The Kola Superdeep Borehole SG-3

The Kola Superdeep Borehole SG-3 in Russia is the world's deepest (Image: Rakot13/CC BY-SA 3.0)

A record-breaking hole dug deeper into the Earth than the height passenger aircraft fly above it was eventually sealed shut after scientists reported hearing a "sound like hell".

The Kola Superdeep Borehole SG-3 in Russia was the product of a scientific Cold War race between the Soviets and the USA to acheive new feats in underground exploration.

In 1989, just a few years before the collapse of the Soviet Union, the Communist nation won the battle by reaching a staggering depth of 7.6 miles, or 40,230 feet, at a site in the Pechengsky District of the Kola Peninsula, close to the border with Norway.

The borehole remains the furthest mankind has ever delved towards the centre of this planet, and scientists made some remarkable discoveries on the way.

At the deepest depths of the hole temperatures of the surrounding rock reached an astonishing 180C, around double the heat researchers had predicted.

Russia's Kola Superdeep Borehole

Russia's Kola Superdeep Borehole sits near the Arctic Circle in the Kola Peninsula (Image: Andre Belozeroff via Wikimedia Commons)

On average the distance to the molten core of the Earth is around 4,000 miles, which is still a lot deeper than the Soviets, or anyone else, has so far managed to dig.

Extreme temperatures reaching above 4,000C at the centre of the planet mean that getting close to anywhere near those depths and pressures is beyond the technology available today.

But scientists did make some interesting discoveries in Russia, including that water could be found nearly four miles down, and beyond that a layer of superheated mud existed.

The researchers also found evidence of microscopic fossil life forms dating back billions of years.

Local reports also claimed the super deep hole emitted a chilling sound which could be picked up by scientists and people living nearby to the chasm-like pit.

A satellite image of the superdeep borehole in Russia

Russia's Kola Superdeep Borehole complex is now abandoned and the hole has been welded shut (Image: Getty )

After the end of the Soviet Union, funding for the 23-centimetre wide hole dried up and by 2007 the buildings and research station had fallen into ruins.

Today a metal lid has been welded over the hole to prevent anyone, or thing, falling down it.

Reports a sound was heard from the hole are disputed, with some claiming apparent scream-like noises were actually created afterwards from recordings from a horror film.

The first account of a sound being reported to have been heard by researchers at the hole was broadcast by a US-based Chrisitan TV station.

The area does remain a tourist attraction, although visitor numbers have fallen since the Russian invasion of Ukraine.

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