Kola Superdeep Borehole reaches record 12,262-meter depth

The Kola Superdeep Borehole (SG-3), located on the Kola Peninsula, remains the deepest man-made penetration into the Earth. Drilling began on May 24, 1970, under the Soviet Union, and the project eventually reached a record depth of 12,262 meters (approximately 7.6 miles) before concluding in 1992 due to physical, financial, and technological constraints.

A scientific review published in February 2026 in the journal Communications Earth & Environment highlights that temperatures at the bottom of the borehole reached 212 degrees Celsius. This intense heat caused plastic rock formations that repeatedly sealed the well.

Despite not reaching the Moho boundary, the SG-3 project provided unprecedented direct data regarding the crystalline continental crust. Researchers note that such data is vital for understanding deep geological processes and the trapped thermal energy beneath the surface, which could inform future enhanced geothermal systems (EGS).