The Dyatlov hikers’ route can be confusing, not least because it is often incorrectly reported. The hikers’ ultimate destination was Otorten Mountain. They intended to scale it and then return home. To get to Otorten, they first had to climb Holatchahl Mountain, sometimes spelled Kholat Syakhl. It was on Holatchahl that all nine of them died, though some sources incorrectly state that they died on Otorten. The name “Holatchahl” comes from the Mansi language, which is part of the Finno-Ugric language family. It means “Dead Mountain,” not “Mountain of the Dead.” Likewise, Otorten is sometimes mistakenly reported to be a Mansi word meaning “Don’t go there,” but Eichar points out that this is also false: “Otorten is not a Russian or Mansi word at all, but simply an error on Russian maps resulting from the mispronunciation of a different mountain a few miles to the north” (334).

Infrasound is low frequency sound below the range of human hearing. Humans can typically hear a range of 20 Hz to 20 kHz (20,000 Hz); infrasound occurs below 20 Hz. Though humans cannot hear infrasound, it can cause various uncomfortable symptoms like “nausea, severe illness, psychological disturbances and even suicide” (319). Infrasound can be caused by natural phenomena, including extreme weather, lightning, earthquakes, and volcanic eruptions, as well as man-made phenomena like sonic booms, nuclear detonations, diesel engines, or wind turbines.