The Soviet Union's Kola Superdeep Borehole reached a depth of 12,262 meters, setting the world record for the deepest hole ever drilled. The project began in 1970 with the aim of drilling 15 kilometers. Drilling ended in 1992, stopped by extreme heat and pressure that made the rock behave plastically, warping and squeezing the borehole shut despite specialized rigs.
How far they got
At 12,262 meters, the borehole on the Kola Peninsula remains the deepest artificial point on Earth. The target of 15 kilometers proved unreachable. The rock at those depths didn't cooperate, and the hardware couldn't hold the hole open.
What stopped the drill
The problem wasn't just the drill bit wearing out. At those depths, temperatures and pressures were so high that the rock itself started to flow like a thick liquid. The borehole walls squeezed inward, warping the shaft and pinching it shut. Specialized rigs that had been built for the job couldn't keep up with a hole that kept closing on itself.
The 22-year run
From 1970 to 1992, the project pushed deeper and deeper in stages, with the longest continuous drilling stretches taking years. The hole wasn't drilled in one go. It took over two decades to reach the record depth, and every extra meter got harder. The final depth of 12,262 meters stands as the deepest point humans have ever drilled into the crust.
What the record still means
The Kola Superdeep Borehole never hit the 15-kilometer mark that planners wanted. But it did reach deeper than any other hole before or since. The project ended because the planet's interior made it impossible to go further, not because the drilling team gave up. The borehole itself still exists, sealed off, a 12-kilometer-deep reminder of where the rock won.
