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How deep is Kola Borehole, world’s deepest man-made hole?
If reports are to go by, the deep drilling race commenced in 1958 with the American initiative known as Project Mohole, aiming to retrieve a mantle sample ... as the Kola Superdeep Borehole ...
The Sun1mon
Earth’s most terrifying holes from 40,000ft Soviet ‘well to hell’ to Mexico’s mysterious 500ft-wide blue ‘sea sinkhole’
The official name for the so-called "well to hell" is the Kola Superdeep Borehole SG-3 – but that's not as catchy. It's currently the deepest man-made hole on Earth, reaching a dizzying 40,230 ...