The Dyatlov Pass Incident

In February 1959, nine experienced hikers died in the Ural Mountains of the Soviet Union under inexplicable circumstances. They cut their way out of their tent in the middle of the night, fled into -30C temperatures in minimal clothing, and scattered. Some had massive internal injuries with no external trauma. One woman was missing her tongue. Soviet investigators concluded the cause was "a compelling natural force." In 2019, Swiss researchers used avalanche simulations to propose a delayed slab avalanche as the trigger — the most scientifically rigorous explanation so far, though not universally accepted. 65 theories have been published.