Mystic Falls is a 70ft cascade type waterfall on the Little Firehole River, a tributary of the Firehole River. Originally named Little Firehole Falls by members of the 1872 Hayden Geologic Survey, the name was changed to Mystic Falls by members of the Arnold Hague Geological Survey in 1885 for unknown reasons.Mystic Falls is reached via the 1.2mi Mystic Falls Trail which starts at Biscuit Basin in the Upper Geyser Basin.