Kola Superdeep Borehole: Soviets Dug World's Deepest Human-Made Hole

For a long time, the Cold War has been going on with the United States and the Soviet Union trading out-of-this-world arms on Earth and even across space. Hence, Soviet physicists dug the world's deepest man-made pit - Kola Superdeep Borehole - to outrun the United States.

According to its website, Kola Superdeep Borehole was the Soviet Union's effort to dig as deeply as possible into the Earth's surface. Hence the scientific drilling project is situated in the Pechengsky District Russian border with Norway, on the Kola Peninsula.

The cavity comprises several other holes, the deepest of which, SG-3, penetrates the Earth's surface to a shocking depth of 12,261 meters (40,226 feet), with the main target depth set at 15,000 meters (49,000 ft). The Uralmash-4E and later the Uralmash-15000 series drilling rigs were used to start the drilling on May 24, 1970.

The diameter of the hole is comparable to the combined heights of Mount Everest and Mount Fuji, and it is higher than the Mariana Trench's deepest point.

US, Soviets 'Ambitious Plans' During the Cold War

You're probably wondering who started the drilling race. Surprisingly, the Americans were successful. GeoScienceWorld said the United States initiated Project Mohole to dig as deep as possible into the Earth's atmosphere, perhaps even into the planet's mantle during the early 1960s.

The proposal was to drill into the seabed from a ship near a volcanic island in the Mexican Pacific. Still, the funding was ultimately canceled by the US Congress due to scientific resistance, mismanagement, and an out-of-control financial problem.

Meanwhile, Russia was almost there. But the Russia Information Center said the country had to abandon the project in 1992 due to higher-than-expected temperatures making drilling deeper unfeasible.

The abandoned Soviet scientific research station is currently located somewhere in the Kola Peninsula. The borehole will be closed using specialized dismantling equipment, according to Russia. It had been partially cemented, according to some.

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Scientific Insights from the Soviets Borehole

Although the project failed, a journal titled "The World's Deepest Well" said the Kola Superdeep Borehole offered geological insights into the Earth's geology and had become a source of detailed geophysical inspections.

Russian scientists believed that the rock at that depth had been thoroughly eroded and was flooded with water was incorrect, provided that the crust 5km down was very thick and rocks should be waterproof. They thought, however, that the water originated from deep-crust minerals that were unable to meet in the atmosphere.

They also found 14 fossilized microorganisms, including microscopic plankton fossils 6 kilometers (4 miles) below the sea. They also confirmed that a significant amount of hydrogen gas was leaking from the cavity. Gold, copper, and nickel deposits were also discovered.

Although the Kola Superdeep Borehole was the world's deepest artificial location, it was best known for its urban legend tale. When Lotte Geevan, a Dutch artist, lowered a microphone into the pit, it was said to pick up a rumbling sound she characterized as "haunting" and "hellish." Others say that it was just the planet's breathing.

About the fact that it made little sense to Soviet physicists, the cavity became known as the "entrance to hell."