The Economic Times

Deeper than the Mariana Trench, near its border with Norway, the Soviet Union spent 20 years drilling 7.6 miles into Earth; in 1992, the deepest borehole on Earth was abandoned in a region industrialization had turned into one of the most poisoned spots on Earth

The Kola Superdeep Borehole, a groundbreaking feat by Soviet engineers, extends over twelve kilometers into the Earth. This ambitious endeavor aimed to explore the Earth's crust and its connection to the mantle. However, the unexpectedly high temperatures led to flowing rock, which complicated the drilling process and transformed geological theories.