Dyatlov Pass incident

The group had originally planned to bypass Mount Kholat Syakhl.

An excerpt from the article 39 facts about Dyatlov Pass incident

Most likely, it was Igor Dyatlov who decided to change the route. To wait out the deteriorating weather, on February 1 the group pitched a tent at the side of the mountain. Notes written in their diaries indicate that everyone was in very good spirits. This is corroborated by various photos of smiling people.