55 Runners Break Record 3,669 Feet Underground in Sweden

Imagine running a marathon in complete darkness, wearing a helmet, with no breeze and dust floating in the air. That's exactly what 55 brave runners did on October 25, 2025, setting a stunning new world record.

The group completed a full marathon at 3,669 feet and 10 inches underground in Sweden's Garpenberg Mine. To put that depth in perspective, it's deeper than two Empire State Buildings stacked on top of each other.

The Garpenberg Mine in south-central Sweden has been operating since the 13th century and is now the world's most productive zinc mining facility. Its shafts reach nearly 4,600 feet underground, though the marathon took place at a slightly shallower level where a suitable loop could be formed.

Getting down to the starting line took a three-minute elevator ride into the depths. Once there, runners faced a muggy 75-degree temperature with 72% humidity and floating dust particles. They had to wear helmets and headlamps as they navigated the pitch-black corridors in total silence.

The course itself presented unique challenges. Since there's no straight path underground, the runners completed 11 laps through a winding loop to reach the required 26.2 miles. The route included stairs and ramps, adding vertical climbs to an already demanding environment.

"Marathons are hard in temporary environments," said Bear Grylls, one of the event's sponsors. "You go into this environment, you clock in the fear and the adrenaline, the intimidation of the environment — it definitely takes it up a few notches."

Despite the harsh conditions, all 55 runners crossed the finish line. They absolutely crushed the previous record of 1,640 feet, set in Germany's Crystal Mine, nearly doubling the depth.

The Ripple Effect

The runners didn't just break records. Their underground journey raised more than $1 million for two worthy causes: Bear Grylls' BecomingX Foundation, which provides education to young people in South African mining communities, and the Wild at Heart Foundation, which supports animal welfare projects worldwide.

As one runner put it after emerging from the depths, "No human has ever run this deep before." They turned an extreme athletic challenge into a force for good, proving that pushing boundaries can lift others up.