The Dyatlov Pass Incident
Sources: https://en.wikipedia.org/wiki/Dyatlov_Pass_incident https://en.wikipedia.org/wiki/Komsomol https://www.theatlantic.com/international/archive/2020/02/russia-dyatlov-pass-conspiracy-theory/605863/ https://earthsky.org/human-world/dyatlov-pass-incident-mystery-solved-slab-avalanche