Kola superdeep well
The Kola experimental reference superdeep well (SG-3) is the deepest mine working in the world. Has scientific significance. It was part of the system of ultra-deep wells in the USSR. Located 15 km east of the village of Nikel and 12 km west of the city of Zapolyarny .
In 1997, it was listed in the Guinness Book of Records as the deepest human invasion of the earth's crust, and remains so to this day. It was also...