Kola Borehole Reached Record Depth

The Kola Superdeep Borehole on Russia's Kola Peninsula near Murmansk in the Arctic reached 40,230 feet, making it the deepest artificial point ever drilled vertically into Earth. Soviet scientists began the research project in 1970 and reached 7 kilometers, about 23,000 feet, within five years. The borehole eventually descended more than 12 kilometers despite measuring only about 9 inches across at its deepest point. It reached its record depth in 1989, and drilling ended in 1992 after temperatures climbed to 356 degrees Fahrenheit instead of the predicted 212 degrees, making further progress impractical.

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