Big Ice Cave

Useful Information

Location: Pryor Mountain National Wild Horse Range, 19 km southeast of the Sage Creek Campground. From Bridger US 310 south for 4 km, turn left on Pryor Mountain Road, after 35 km follow Forest Road 2050 east for 2 km. High clearance vehicles or 4x4 recommended.
Open: 15-JUN to 15-SEP no restrictions.
16-SEP to 14-JUN closed because of hibernating bats.
Fee: free.
Classification: SpeleologyIce cave
Light: not necessary, you may bring a torch
Guided tours:
Address: United States Department of the Interior, Bureau of Land Management, Billings Field Office, 5001 Southgate Drive, Billings, Montana 59102
Beartooth Ranger District, Custer National Forest, HC 49, Box 3420, Red Lodge, MT 59068, Tel: +1-406-446-2103.
As far as we know this information was accurate when it was published (see years in brackets), but may have changed since then.
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Big Ice Cave is a single chamber of the cold trap type, an entrance which goes steep down into a huge chamber. This morphology results in a cold trap, as cold air is heavier than warm air. In winter the cold air "flows" into the cave, in summer it stays there. This works similar to refrigerators in the supermarket, which keep their content frozen although they have no lids. This simple physical effect is the reason why this cave contains ice and icicles year round. And obviously it is the reason for its name.

The cave is not a show cave, although you could say it is developed. A short walk down an improved plank trail into the entrance portal and on a wooden platform inside the cave where visitors can see the always present ice floor of the cave. There are no guided tours, no speleothems and not much to say about the cave. Take a sweatshirt or jacket, it may be cold inside.

The cave is located in the Pryor Mountains, which are riddled with caves. The most visited is Big Ice Cave, which may be visited freely. All others can be explored only with a permit from the Forest Service or the BLM.