George R. B. Kinney [1872–1961], a member of the 1911 Alpine Club of Canada–Smithsonian Robson Expedition to the Mount Robson region in 1911, discovered the cave in the Arctomys Valley in 1911.

“In the valley where the stream has its origin, Kinney discovered a rock opening which seemed to lead into the bowels of the earth,” wrote expedition leader Arthur Oliver Wheeler [1860–1945]. “It is evidently a rift in the strata, which here dips steeply. This through the action of water, has been widened into a deep shaft leading down, goodness knows how deep. …

“The shaft, it can hardly be called a cave, was examined with candle, rope and barometer. The opening, a slit in a shallow depression, at one time undoubtedly furnished a water exit to lower levels. It is only large enough to admit one at a time. We descended 250 feet by barometer measurements to a point where a small stream of water tumbles through a tributary crack. Beyond that the going is wet and the exploration was not carried further, as there was no change in the character of the subterranean shaft. Kinney claimed that, at the time of his discovery, he had gone some distance beyond the fall. The crack descends at an angle of about 65 deg. or 70 deg. from the horizontal. The rock is hard and rough, and affords food hand and foot holds. In places the width is ten to twenty feet and minor cracks lead off here and there. The walls are a dark limestone, dun colored on the outside surface from seepage of the lime. There were no stalactites more than two or three inches length, and, generally speaking, it was unattractive. It appeared to be one of these subterranean waterways that are frequently encountered in mountains of a limestone formation.”

There is no record of subsequent visitation until 1971–1973 when cavers from the McMaster University Climbing and Caving Club, Guelph University Caving Club, Alberta Speleological Society and some visiting British cavers explored and surveyed the cave to its maximum depth of -522 metres. Passages above the entrance were surveyed by British and Canadian cavers in 1983 resulting in the current vertical range of 536 metres. Arctomys Cave was the deepest known cave in Canada for many years, until surpassed by Bisaro Anima Cave in 2017 with its depth of 670 metres.

Arctomys Cave is formed in the steeply-dipping Mural Formation limestone of the Early Cambrian Gog Group. The top half of the cave (The Endless Climb) descends relatively steeply, but at a depth of about 400 metres the cave becomes more horizontal with several pools, and ends at a sump. Despite its great depth, the cave includes only five pitches up to 15m deep. Although most of the cave is undecorated, the Straw Gallery has flowstone and relatively long soda straws.

Arctomys Cave is the site of Canada’s most extensive cave rescue attempt. On October 17, 1991, Rick Blak, an experienced caver and park ranger at Mount Robson Park, was struck by a falling boulder deep in the cave and perished. One hundred and ten people were involved in the complex recovery of his body.

According to the the Mount Robson Park management plan (2011), “Arctomys Cave holds some attraction to both domestic and international cavers, but it receives only very light use, largely owing to its remote location. Caving is not promoted in the park; however, it is recognized as an appropriate activity.”