Dyatlov Pass Incident
The Dyatlov Pass Incident is the unsolved disappearance of nine hikers in the Ural mountains in Russia in 1959, and subsequent discovery. There’s a whole lot of details to this case which are mentioned in the link, but for a brief summary:
Ten experienced ski hikers embark upon a trek through a mountain pass that locals describe as “Devil’s Pass.”
One of the hikers returns on his own due to illness. The others continue ahead. After the party don’t return when expected, a search party is sent out into the mountains to look for them. Their campsite was eventually found, abandoned and slashed open from the inside, and the bodies were eventually all found at various points nearby in various unusual states, including some naked or undressed, some with their heads basically smashed in (which later investigations showed were impossible to have been done by humans).
This is a conspiracy theorist’s wet dream, with details that don’t add up, Cold War/KGB cover-ups, UFO sightings, cryptozoology (yeti theories), weapons testing, nuclear radiation emanating from the bodies, stories of local savage tribes etc. But even without all that, it’s still a pretty eerie story on its own.
Dyatlov Pass is a total rabbit hole and it’s one of my personal favorite mysteries.