The Guinness World Records award for "the deepest human invasion into the Earth's crust" goes to the Kola Superdeep Borehole. Its depth is 7.4 mi. You can find it in the icy part of Russia where the winter temperature of -40°F is a common thing. Local scientists started to dig it in the 1970s. The grand plan was to reach the depth of 9.3 mi. It was a purely scientific project to study the Earth's crust and maybe get to the hot mantle.

Up to the depth of 4.3 mi, the drill easily coped with granite rock. Then, denser layers came and broke the drill. The scientists had to change the drilling pattern. In the end, it resembled a tree with many branches. The deeper it went, the hotter it became. The temperature went up to 350°F. The equipment was constantly out of order and work was stopped completely in 1992. The place is now abandoned, overgrown with moss and rust. But it has its fair share of myths surrounding it too...

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