What Scientists Found Inside the Deepest Hole on Earth Astonished Everyone

The Kola Superdeep Borehole was not wide, spectacular, or open like a giant cave. At the surface, it was only a narrow drilling shaft on Russia’s Kola Peninsula.

But it went deeper into Earth than any human-made hole had ever gone. The Soviet project began in 1970 and eventually reached 12,262 meters, or about 7.6 miles, below the surface.

The goal was to study Earth’s crust directly, but the deeper scientists drilled, the more the ground stopped behaving the way they expected. What they found changed assumptions about heat, rock, water, fossils, and the hidden structure beneath our feet.