Named in relation to Arctomys Valley, in turn so-named in 1911 because of the numbers of hoary marmots in the area (Expedition to Jasper Park, Yellowhead Pass and Mount Robson, by A.O. Wheeler, published in Canadian Alpine Journal, vol IV, 1912, p.24&25). The cave is described but not named in the same article. Mis-spelled (with possesive apostrophe) as "Arctomy's Cave" in Globe & Mail article: Canada's Deepest Cave Found in BC..., 26 September 1973 (file J.1.49). See also "Exploring Canada's Deepest Cave", Canadian Geographic magazine, Vol 90, No 1, January 1975, p4.
Source: BC place name cards, or correspondence to/from BC's Chief Geographer or BC Geographical Names Office