Superdeep Hole in the Earth Plunges Deeper than Mount Everest Is Tall

Abandoned Kola ultra-deep well (borehole) near the town of Zapolyarny, Pechengsky district, Murmansk region, July 2022

Superdeep Hole in the Earth Plunges Deeper than Mount Everest Is Tall

Located in the Murmansk Oblast in Russia is a superdeep hole that defies imagination. The Kola Superdeep Borehole is proof of man’s curiosity about the world around us. Until very recently, the site was home to the deepest hole in the entire planet. Time to dive down the rabbit hole and find out why this massive hole exists.

The SG Program

superdeep hole
While the Kola site was once the home of the deepest hole in the world, it is now long abandoned.

The SG Program is a directive from the Soviet government of the time for research into the Earth’s actual composition. The superdeep hole at the heart of this list is the most notable of the SG Program, which lasted well into the 1990s.

Previous Borehole Sites

superdeep hole
The main facility was once teeming with life, however, the lack of funding has led to it falling into disrepair.

Before the aforementioned superdeep hole, it bears mention to look at its forebears. Aralsor SG-1 is the earliest of these sites and is located near the Caspian Basin in western Kazakhstan. Biyizkhal SG-2 is located in Krasnodar Krai in southern Russia. Neither one of these superdeep hole sites would exceed 22,340 feet in depth.

Kola SG-3

superdeep hole
Volunteers of the Clean Arctic learn about the history of the facility before starting their work.

1970 saw the start of the Kola Superdeep Borehole. Dubbed SG-3, this borehole would be the most successful under the Soviet initiative. While similar in concept to the likes of an oil well, there were no monetary gains to be made with this superdeep hole.

The Equipment Used

superdeep hole
Despite the immense progress made, the Kola SG-3 site has been abandoned since 2008.

Kola SG-3 utilized the Uralmash-4E, a drilling rig intended for oil wells. Specialized modifications were made to allow for the drill to reach 23,000 feet in depth. After four years with the Uralmash-4E, this superdeep hole received an upgrade in the Uralmash-15000. This specialized drilling rig could reach even further, with a maximum operational depth of 49,000 feet.

International Appeal

Kola Sg-3
All that remains of the site in 2024 is the former hole site, which has been welded shut.

It didn’t take long for the superdeep hole in the Kola peninsula to attract international interest. Despite the somewhat frosty international politics of the Cold War, researchers from all over the world would venture to the Soviet Union to participate in the project. Scientists from the United States, Scotland, and Norway would all be part of the proceedings.

Research Revelations

Kola SG-3
Taken in 2022, this photo shows all the remaining buildings before their demolition.
©Шелковников Евгений Анатольевич / CC BY-SA 4.0 - Original / License

The superdeep hole revealed secrets about the composition of the ground below us in a way mere theory and conjecture couldn’t. Expectations of basaltic layers of rock were dashed when the drill had reached 4.3 miles down into the earth. Curiously, researchers would find the existence of microscopic plankton fossils dating back millions of years.

The Borehole’s End

Kola SG-3
Just a decade prior, the former site of Kola SG-3 was left in a state of absolute squalor.

As with any Soviet initiative, the Kola superdeep hole would come to an end after the fall of the nation. It struggled on for a few years, continuing work well into 1994. Eventually, work would stop in 1995, as a general lack of funding made it impossible. The superdeep hole serves as a tourist attraction but has been abandoned since 2008.


Kola SG-3
The former prestige of this site is captured in a postage stamp made in 1987, just two years before it would break the world record.

At 40,230 feet or roughly 7.6 miles, the Kola site held the record starting in 1989. As with any superdeep hole, depth is the most important measurement. Until 2008, the Kola SG-3 site was the deepest man-made hole in existence. Nonetheless, the record has since been broken by a site in Qatar intended for hydrocarbon extraction.

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