Humans have drilled about 12.2 kilometers (7.6 miles) into the Earth, which is only a tiny fraction of the way to the planet’s center.

Quick Scoop: Record Depth

  • The deepest hole ever made is the Kola Superdeep Borehole in Russia, reaching 12,262 meters (40,230 feet) below the surface.
  • That is roughly one-third of the way through the continental crust in that region, and far less than 1% of the distance to Earth’s core.

Why We Stopped There

  • As the drill went deeper, temperatures rose to around 180–190 °C, much hotter than expected, making rock softer and harder to drill.
  • High pressure and unstable, plastically deforming rock caused the borehole to start closing and equipment to fail, which finally ended the project.

How That Compares

  • Earth’s radius is about 6,371 kilometers, so 12.2 kilometers is less than 0.2% of the way to the center.
  • Even Earth’s continental crust often exceeds 30 kilometers thick, so the deepest borehole has not yet reached the mantle beneath continents.

Newer Deep-Drilling Efforts

  • Recent ultra-deep projects, such as China’s Shendi Take 1 borehole in the Tarim Basin, target depths of over 10 kilometers to study deep crustal rocks.
  • Despite these advances, Kola still holds the record for maximum depth below the surface, while newer wells mainly compete in total length rather than vertical depth.

Why This Matters

  • Deep drilling reveals unexpected rock types, fluid-filled fractures, and temperature profiles that reshape models of Earth’s crust.
  • Data from such projects help in geothermal energy research, understanding earthquakes, and refining theories about how continents evolve over geologic time.

Information gathered from public forums or data available on the internet and portrayed here.