The Dyatlov Pass Incident is arguably the most popular conspiracy theory originating from Russia. According to official sources, the incident is real- along with details that are commonly known.
A group of hikers from the Ural Polytechnical Institute were found with remnants of radioactivity, a missing tent, and missing tongues, prompting much questioning in Russia about what possibly happened. Six died from hypothermia, others had fractured bones and missing eyes. Some argued a "compelling mysterious force", caused the incident.
“”The hikers were buried under several meters of snow [and had] insufficient clothing for sub-zero temperatures, a tent ripped apart from the inside, remnants of radioactivity, a missing tongue.
One such explanation is that the furnace or stove warmer contraption that the team used had caught the tent on fire and then the team tried to put it out. some abandoned the tent with severe burns into the freezing cold wilderness and fell down a short embankment causing the bone fractures. Some time later wild animals tried to scavenge their corpses taking their tongues out. The radiation was explained due to the radium compasses that the team had for it to glow in the dark 
- Lemmino The Dyatlov Pass Case (on Youtube)