The canard: dig deep enough, and you’ll come out in China. As children, we all tried it, impossible as it may be. There is a certain human desire to push the limits and see just how tall we can make a building, how fast we can fly a plane, or, in the case of the Kola Superdeep Borehole (the silo of which is pictured above), how far below the Earth’s surface we can dig.
A project of the USSR in the early 1970s, the Borehole had a clear goal: dig as deep as humanly possible. The Borehole is actually a series of boreholes, and the deepest one — while only 8 inches wide — extends over seven and a half miles below the surface. That’s more than 40,000 feet down. (And, had it extended all the way through the Earth’s core — the physics and geological issues notwithstanding — the borehole would come out, roughly, here.)
How deep is 40,000 feet? Imagine if you laid the Willis (formerly Sears) Tower, the Empire State Building, and Seattle’s Space Needle one on top of the other. They’d reach a combined height of rougly 3,800 feet, less than 10% of the depth of the Kola Superdeep Borehole.
And the plans for the Borehole were even deeper. The Soviets wanted to go to nearly 50,000 feet. What stopped them? The heat. As they reached their current, final depth, temperatures reached 180 degrees Celsius, and with the additional heat created by the drill bit, the environment became too difficult to warrant further work.
From the Archives: Underwater Repairmen: People who fix problems way, way down deep.
Related: A hole digger of some sort. Probably won’t get you down eight miles.