What Did We Find Inside the World’s Deepest Hole? (Kola Superdeep Borehole) | Smartest Year Ever (Jun 7, 2025)

What’s the deepest hole humans have ever dug? And what did we find when we got there?

In this episode, Gordy explores the mind-bending story of the Kola Superdeep Borehole, a Cold War-era Soviet project that went deeper into the Earth than any drill had ever gone before — and hasn’t been surpassed since.

While space exploration was captivating the world’s imagination, the Soviet Union decided to turn its attention downward — attempting to punch through the Earth’s crust and see what secrets might be buried beneath our feet.

What they found challenged everything we thought we knew about geology, heat, pressure, and even life itself. From underground water sealed off for millions of years to fossils where no one expected them… this wasn’t just a science experiment — it became a legend.

Why did the project get abandoned? What made it so difficult to dig that deep? And are the rumors about “sounds from hell” complete nonsense — or based in something real?

This is one of those stories that makes you feel small… and a little creeped out.

Don’t miss this one.

Sources

• Pease, M. (1990). Drilling to the Earth’s Mantle: The Kola Superdeep Borehole. Scientific American.
  

• Wright, S. (2016). How Deep Is the Deepest Hole Ever Dug? BBC Future. https://www.bbc.com/future/article/20160526-how-deep-can-you-dig
  

• Smith, J. (2021). What Did We Find at the Bottom of the Kola Superdeep Borehole? National Geographic.
  

• Kola Science Center. (1995). Geological Discoveries at the Kola Superdeep Borehole. Russian Academy of Sciences.
  

Music thanks to Zapsplat #EarthScience #SmartestYearEver #ColdWarHistory #GeologyFacts #KolaBorehole #DeepestHole #SovietUnion #ScienceMysteries #Underground #DidYouKnow