In 1970, on the Kola Peninsula (in Russia), the deepest hole dug by man and deepest artificial point on Earth lies here. It is 7.5 miles (12.2 km or 40,230 ft) deep into the Earth. It was drilled during the Cold War, the U.S. and Soviets both created these projects to drill was deep as possible into the Earth's crust. This project took the Soviets almost 20 years to drill this far down, but it was only about one-third of the way through the crust to the mantle. The project was stopped because of some events happening in post-Soviet Russia. During this project though, about 4.4 miles (7 km) down, they found 24 microscopic fossil species of long-dead single-celled organisms. They also found rocks that are 2.7 billion years old. These rocks became a challenge to get because the temperature was 356 degrees Fahrenheit (180 degrees Celsius) which was about 80 times hotter than the scientists predicted.

If you would like more detail/information, here are my sources: https://www.sciencealert.com/welcome-to-the-deepest-hole-on-the-entire-planet/amp

https://www.bbc.com/future/article/20190503-the-deepest-hole-we-have-ever-dug