The quarry was abandoned long ago and immediately attracted fans of adventure sport. Mostly because it’s one of the most demanding networks of tunnels for cavers anywhere in the Moscow region.

But the sport can be dangerous – four people have died in these caves over the years, so the quarry was blown up by local authorities. But soon the cavers came back to restore their former playground. To try and avoid future casualties, they came up with a system to improve safety and presented a registry journal – everyone who comes in the cave has to check in and check out when they leave. So in case of emergency, rescuers know how many people are inside and who they are.

But emergency workers don't think these measures go far enough. These caves are so difficult to get into that the chances of saving someone trapped here are very small.

Even so, the place remains an attraction for adventurers who go underground at their own risk.

The guide named Michman found the cave when he was 10 years old. Years later, an experienced caver guided him through it. Since then he's been going underground every weekend.

“In the beginning I liked doing it because of the surreal feelings and then I began to explore the space to see what's behind the blockage. In 12 years, our team has dug 5 kilometers of tunnels in these caves!” Michman says.

These days, Michman takes his family and friends to the tunnels, and guides other enthusiasts around the caves he's been digging for nearly 15 years.

There are some who come down to the caves out of curiosity. Others want to hide from the noise and the stress of the outside world. And there are those who seek extreme adventures underground and they take no flashlights with them.