In early February 1959, nine Russian hikers died in the northern Ural Mountains in unknown circumstances. At some point in the night, the hikers cut open their tent and walked away from their tent in inadequate clothing, no boots or winter jackets. Three of them died from physical trauma similar to a car accident. The other six died from hypothermia, but one also had a small skull fracture. The bodies were found hapazardly about a mile from the tent.

The various theories considered include:

• Mansi people attacked and murdered the group, but evidence does not support this idea.
• Avalanche
• Kabatic wind
• Infrasound generated by wind drove the hikers mad.
• A military parachute mine exercise.

A military parachute mine exercise is a strong theory. These exercises were being conducted at the time. It is suggested that the hikers were woken by loud explosions. Injuries of the mine would match the trauma from the three that died of trauma. The theory coincides with reported lights and photographs from the hikers. Some of the hikers had high levels of radiation on their clothes which would match a radiological weapons test. The files were kept secret.

The initial investigation concluded that the group died of a compelling natural force. And the files were sent to a secret archive. The investigation was reopened in 2019 and the conclusion in July of 2020 was that an avalanche forces them to suddenly leave their tent in low visibility conditions.

However there is evidence that contradicts the avalanche theory. The location did not have signs of an avalanche, nor is it known for avalanches based on history and terrain. There were two very experienced hikers that would not have camped near a potential avalanche site. The footprints were of people walking away from the tent at a normal pace not running in panic

A 2015 investigation suggests that a snowfield above the tent starts to slide down over the tent. The hikers escape through a cut hole, with incomplete clothing, and descend the slope to find a spot safe from an avalanche. They split up into three groups. The ones with least clothing stayed by the fire and dies of hypothermia, one group went to the tent for clothes and died of hypothermia on their way, and the last group were trying to find a better place to camp but fell into a snow hole dying of trauma.