On this day in 1959, nine Soviet students died in the Ural Mountains under bizarre circumstances in what has become known as the Dyatlov Pass Incident. The group was sheltering from a storm when some unknown event caused them to cut a hole in their tent and flee, many of them without shoes or jackets. Six died of hypothermia, and three died of unexplained physical trauma described as “a compelling natural force” by investigators. The condition and location of the bodies have inspired wild speculation about what could be responsible, including aliens, Yeti, or top-secret military testing. Further clouding the issue is the less-than-transparent handling of the official investigation by Soviet authorities, galvanizing this as one of the greatest mysteries of the 20th century.