The Kola Superdeep Borehole, although only 9 inches in diameter, holds the distinction of being the deepest hole, plunging to ... delving deeper than any other man-made structure.

America might have landed on the moon, but Russia drilled the deepest man-made hole on Earth. Since the early 1960s, scientists have attempted to drill down to the Earth's mantle. It took 20 years ...

The project was started during the Cold War era, as the Soviet Union had the ambition to create the deepest man made hole ever. Despite going so deep, the borehole was eventually sealed for ...