The Deepest Hole Ever Dug

The deepest hole ever dug is indeed the Kola Superdeep Borehole, reaching a depth of about 7.6 miles (12.2 kilometers). This is a small fraction, less than 0.2%, of the distance to Earth's core.

That’s like poking a thumbtack into a basketball and calling it a tunnel.

Started by Soviet scientists in 1970, the Kola Borehole was an attempt to better understand what lies beneath our feet. They kept drilling for over two decades, eventually reaching temperatures above 350°F, hot enough to cook a pizza. But the deeper they went, the tougher the rock and heat became, until the project was finally abandoned in 1992.

Surprisingly, even at this depth, they didn’t reach the mantle. Just the crust.

And what did they find? Fossilized plankton nearly four miles down, and water—yes, water—trapped inside rocks. Imagine a place darker than space, hotter than a desert, and still holding ancient microscopic life.

To get to the Earth’s core, we’d need to dig another 3,900 miles. That’s like lining up about 740 Mount Everests end to end.

So while the Kola Superdeep Borehole is the deepest manmade hole on Earth, it's barely more than a scratch on the planet’s surface.