Kola Superdeep Borehole – The World’s Deepest Artificial Hole

Mankind has always been curious about everything around us, and in order to satisfy this desire to know and discover, it has tried the craziest experiments. One of these experiments was the one called the Kola Superdeep Borehole.

The Kola Superdeep Borehole is the deepest artificial hole on Earth, and it is a result of a project started by the Soviet Union in 1970. The purpose of the project was to find out more about the contents of the planet’s crust and to try to drill as deep as possible into the earth’s crust.

Thus, on May 24, 1970, the USSR decided to start drilling in the Kola Peninsula, which is located near the Russian border with Norway.

How deep is the Kola Superdeep Borehole?

In order to surpass the Oklahoma hole record (Bertha Rogers) of 31,440 ft (9,583 m), the original depth had been set at 49,212 ft (15,000 m). In 1983, the Kola Superdeep Borehole broke the record for the Oklahoma hole, reaching a depth of 12,000 m. But the maximum depth of 40,230 ft (12,262 m) was reached in 1989.

How deep is the Kola Superdeep Borehole
How deep is the Kola Superdeep Borehole? Author: Sebastián Tavella
Ruins of the Kola Superdeep Borehole site facilities
Ruins of the Kola Superdeep Borehole site facilities

How did they drill the Kola Superdeep Borehole?

Work on the world’s deepest hole began with two drilling tools called the Uralmash-4E and the Uralmash-15000.

Kola Superdeep Borehole - The World's Deepest Artificial Hole - Uralmash-15000 drilling rig
Kola Superdeep Borehole – The World’s Deepest Artificial Hole – Uralmash-15000 drilling rig

What was found in the Kola Superdeep Borehole?

The first thing discovered by digging Kola Superdeep Borehole was the existence of water 7.45 mi (12 km) deep in the Earth’s crust. This astonished scientists who continued to research the water’s source. According to them, the water came from minerals and was prevented from reaching above by a layer of impermeable rock.

Another discovery was the microscopic fossils of 24 species of dead single-celled organisms, and a large quantity of hydrogen gas. The researchers described the mud in the hole as “boiling” with hydrogen.

How long did it take to dig the Kola Superdeep Borehole?

The drilling for Kola Superdeep Borehole lasted 24 years (1970-1995).

The Kola Superdeep Borehole in 2012
The Kola Superdeep Borehole in 2012. Author: Bigest

Why did they stop digging the deepest hole in the world?

Drilling was stopped in 1989 at a depth of 40,230 ft (12,262 m) because the temperature had exceeded 212°F (or 100 °C), reaching 356 °F (or 180 °C). If the drilling had continued, it would have reached a temperature of 572°F (or 300°C), at which the equipment could no longer operate.

Kola Superdeep Borehole (SG-3)
Kola Superdeep Borehole (SG-3)

What is the temperature at the bottom of the Kola Superdeep Borehole?

At the bottom of the hole, the temperature reached 356 °F (or 180 °C).

Can you visit the Kola Borehole?

Yes, you can visit the Kola Superdeep Borehole. It is located 10 kilometers north of the town of Zapolyarny, in the Pechengsky District of Murmansk Oblast, Russia, and the best suitable way to travel to it is by car.

Superstructure of the Kola Superdeep Borehole, 2007
The superstructure of the Kola Superdeep Borehole, 2007. Author: Andre Belozeroff

Has anyone been to the mantle?

Although there have been many attempts, no one has ever drilled into the mantle. Not yet!

What are the other deepest holes in the world?

In the top of the deepest holes in the world, the Kola Superdeep Borehole is the first, being followed by:

2. Sakhalin

The Sakhalin hole is located in Russia, and it is part of the Sakhalin-1 project, which aims to extract oil and gas. It has a depth of 40,502 ft (12,345 m) that was reached on January 28, 2011.

3. Deepwater Horizon

Deepwater Horizon is known for drilling the deepest oil well in the world at 35,050 ft (10,682 m), but also for the disaster caused in 2010 when nearly five million barrels of oil spilled into the Gulf of Mexico.

4. Bertha Rogers

Situated in Washita County, Oklahoma, the Bertha Rogers hole has a depth of 31,441 feet, which was reached in 1974. The drilling aimed to search for natural gas deposits.

The Bertha Rogers hole
The Bertha Rogers hole. Source

5. KTB Borehole

KTB Borehole was a german project in Windischeschenbach, Bavaria. Drilled between 1987 and 1995, the KTB Borehole reached a depth of 29,859 ft (8,796 m) and stopped due to a high temperature of over 500°F (or 260°C). Now, the KTB Borehole is one of the major German tourist destinations.

KTB Borehole
KTB Borehole. Source

6. Geothermal Engineering Ltd

In 2018, the Geothermal Engineering company began drilling a hole in Cornwall, England. The hole, which was intended to supply electricity from underground hot rocks, reached a depth of 16,000 ft  (4,876 m) in 2019.

Geothermal Engineering Ltd
Geothermal Engineering Ltd. Source

7. Chikyū

As part of the program called Integrated Ocean Drilling, Chikyū was drilled in Japan to study the seafloor environments. The drill started in January 2002, and by April 2012, the Chikyū reached a depth of 25,400 feet below sea level.

Ocean Drilling, Chikyu
Ocean Drilling, Chikyu. Author: Gleam

8. IceCube Neutrino Observatory

The IceCube Neutrino Observatory can be found in Antarctica, at the Amundsen-Scott South Pole Station. This hole was drilled to detect subatomic particles as neutrinos and reached 8,000 ft (2,438 m ).

9. Bingham Canyon Mine

Bingham Canyon Mine is not a hole per se, but it is known as the deepest open-pit mine in the world, and the most productive copper mine in history, having a depth of 4,000 ft(1,219 m).

10. Chuquicamata

As the previous hole, Chuquicamata is also popular for its production of copper. It is located in the north of Chile and has early 3,000 ft (913 m) deep.

Chuquicamata - The World's Deepest Artificial Hole
Chuquicamata. Author: Diego Delso

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