One of the vast caverns in Dark Star is a scary places – a huge cave system tucked inside the Baisun-Tau mountain range in an isolated region of Uzbekistan. Political instability and its remote location have kept the depths of Dark Star (named after a 1974 sci-fi comedy film) hidden from human eyes. But in 1990, a British team managed to reach one of the entrancesand so exploration of this dark underworld began. Around 17km of passages, along with additional entrances, have since been discovered, but all of the openings sit halfway up a 200m-high limestone cliff. And just getting to the base camp at its foot is a long and treacherous journey.

160km along part of the ancient Silk Road towards Samarqand, at the foot of the Baisun-Tau mountain range. More is known about the relief of Mars than about what is hidden under the surface of the Earth. Kruber Cave in the Republic of Georgia is currently the deepest known cave, reaching 7208 feet. But Dark Star, with so many areas yet to be explored, is a prime candidate for this title. To date, eight expeditions have identified nearly 11 miles of Dark Star passages, the deepest of which is about 3,000 feet below the earth’s surface. As you might expect from a cave system so big, it’s dark. Really dark. The light from the surface is mostly absorbed and diffused by the time you get into the lower cave, leaving you in total darkness.

And though the caves have been fully mapped, unless you’re a professional with deep knowledge of Dark Star, there’s a good chance of getting lost in the twisting labyrinth. Your usual navigation devices won’t work with that much natural insulation between you and the cell towers and satellites that provide your position data, and if you run out of battery power for your flashlight, you’ll be left entirely blind. Something about starving inside a miles-long stone coffin doesn’t sound very pleasant, so it’s best to leave the Dark Star Cave excursions to the professionals.