The internet has no shortage of mysteries for those inclined to chase them. Many fit neatly within genres with dedicated fan bases: true crime, Bigfoot, unexplained lights in the sky. But some are so inexplicable, so disturbing, that they worm their way into nearly every corner of the internet’s ever-rolling theory-machine. These mysteries seem to not only defy explanation, but they even befuddle many of those who are quick to attribute such events to the supernatural.

One such incident took place in the unforgiving wilderness of Russia’s Ural Mountains in January of 1959. Ten experienced hikers—nine students from the Ural Polytechnical Institute along with one older ski instructor—set out to conquer Otorten Mountain, a peak in the northern portion of the mountain range. They began their journey by train, traveling to the Soviet city of Ivdel. There they boarded a bus that took them to Vizhay. From there, they took a truck even farther into the frigid forest, arriving in an area known only to local loggers as “Sector 41.”

(Russian National Archive)

From there, a local logger led the intrepid group to an abandoned geological site known as “Nord 2,” where they made camp for a day. There, in the last bit of truly “settled” territory they would come across for days, one of the hikers, Yuri Yudin, fell ill. Over the course of the following day, Yudin took it easy, collecting rock samples for the Institute of Mining back at Sverdlovsk and hoping his illness was nothing but a temporary setback. The following day, however, Yudin acknowledged that his health wouldn’t allow him to continue the trip, so he parted ways with the nine remaining hikers as they set off on their way. That was the last time Yudin would see any of his friends alive.

The Dyatlov Pass students as they hiked toward Otorten mountain. (Russian National Archive)

The remaining nine hikers, led by experienced mountaineer Igor Dyatlov, set out on their trip and, according to photographs and journal entries discovered later, were in high spirits despite some nasty weather and the rigorous difficulty of covering miles through deep snow. They snapped photographs along the way, most of which look like they could have been taken by any group of college kids on such a wilderness adventure today.

Dubinina, Krivonischenko, Thibeaux-Brignolles, and Slobodin having a good time. (Russian National Archive)

Then, on February 1, the tenth day of the hike, Dyatlov’s party stopped and made camp on the eastern ridge of a mountain known only as “Height 1079.” According to some reports, they found their way there as a result of getting lost due to low visibility caused by the winter weather, and for some reason, chose to establish their camp on the slope of the mountain.

The area’s indigenous population, a tribe that call themselves the Mansi, have a different name for that mountain: “Holatchahl.” Mountain of the Dead.

Had they walked only about a mile farther, they would have found flatter ground and more natural protection from the elements. Why Dyatlov chose that area remains a mystery. Some contend he didn’t want to sacrifice the altitude so they could begin the next morning with a downhill hike. Others say he may have wanted to practice mountain slope camping. In any event, that decision may have cost the entire party their lives.

Last known photo of the nine students alive, taken at the camp on Kholat Syakhl. (Russian National Archive)

Before the sun rose again over the Ural Mountains, all nine members of Dyatlov’s party were dead. Objectively, the deaths of nine adventurers on a frigid, snow-covered mountainside in Russia may sound tragic, but not unusual. These types of journeys are inherently dangerous, which, one could contend, is why they offer such allure. But it wasn’t that the hikers all died that earned the Dyatlov Incident its place among the greatest mysteries of the Soviet era, it’s how they died that continues to prompt new theories to this day.