Answer:
The Dyatlov Pass incident
Explanation:
One of the unsolved mysteries that occurred in the 20th century is the Dyatlov Pass incident. Nine Russian hikers were found dead in the Ural Mountain and this took place between February 1 and 2 in 1959. The reason for their death till today is not known. However, it is believed that the Russian Government have opened investigations to find answers to unresolved questions.
