Big Pryor Mountain
Montana's Big Pryor Mountain is aptly named; to most mountaineers, this peak is quite uninspiring because at first glance it is nothing more than one of those big and broad forested humps that appears to offer nothing of interest. So, after living within view of it for the better part of two decades, I reluctantly decided to take a trip to its summit after climbing pretty much every other summit I could find in the area and telling myself repeatedly that "the views from something that high must good." I am happy to report that the trip was well worth it, and there really are some beautiful things to see and explore on this mountain!
Big Pryor Mountain ranks 105th on the continental United States prominence list with 4,296 feet of prominence, and ranks 10th on the Montana prominence list. With a summit elevation of 8,786 feet, it is not high compared to the peaks in the nearby ranges (Big Horns, Absarokas, and Beartooths), but it dominates the northern end of Wyoming's Big Horn Basin.
The Pryor Mountains are full of wonderful ice caves, the biggest of which is located high on the western side of East Pryor Mountain. In addition to some pretty impressive views, the big bonus of reaching the summit of Big Pryor is that there is a small but impressive ice cave located just a couple of hundred yards east of the top.
Summit view towards the Big Horns
Getting There and Hiking Information
Entering Custer National Forest From Tie Flat Road
While you can drive a 4WD vehicle or four-wheeler to the summit from long and rough dirt roads leading from near the towns of Cowley and Deaver Wyoming, the standard approach begins near Bridger, Montana and ends up on a National Forest road just north of the summit, where it is an easy hike to the top. While this dirt road is long as well, the majority of it is easy to drive and goes by quickly.
About 3.0 miles south of Bridger, turn east on Pryor Mountain Road at a brown sign that says "National Forest Access." Zero your odometer here and drive the road as it climbs to Bowler Flats, turning left at an intersection next to a transformer about 12 miles down the road. The road then goes through some sharp turns for 3.0 miles as it runs along property lines before crossing into the Crow Reservation. The next 7.0 miles are the worst part of the road, and include some rocky areas that would be tough in a low clearance vehicle. 4WD isn't necessary unless it is raining, and I would avoid the roads completely in bad weather, as the red clay stuff becomes absolutely awful when it is wet! Once you cross into the Custer National Forest, drive for another 8.0 miles on a much better road to a right turn on Road #2104, which is marked as Tie Flat Road. The total distance to this point is about 30.0 miles.
Almost immediately after turning on Tie Flat Road, take a right turn on a rough 4WD road marked as #21041. According to the Pryor Coalition website, motorized travel is not legal on this road, but there are no signs marking otherwise. I drove a quarter of a mile up this road to a part where it started to get steep and parked, but it's probably best to park at the turn on #21041 because driving any farther doesn't gain you much.
Start looking here The trail
Walk up the road to an intersection of several 4WD roads and walk about 150 feet to the left, looking for a gully on the right. There is an unmaintained trail that leads up the mountain from here, but finding the start of it is tricky. Dennis Poulin assembled a cairn of three white rocks in July 2011 marking where to leave the road; the cairn was still there when I visited the peak a month later, but they may or may not still be there in the future. The lower part of the trail has some sections of deadfall that aren't easy to navigate, but it gets better as you go up. This trail switchbacks all of the way to the top, but it is faint in places, and some of the switchbacks are easily missed because game trails often continue straight on at places where you should turn. I got way off trail about halfway up and finally just headed straight up with an occasional heated remark aimed in the direction of the trees that always seemed to be in my way. I found the spot where I went wrong on the way down the trail, and put a log down to block the bad trail.
Approaching the summit At the top!
The summit is marked with a giant cairn and a large pole. The Shriver BM is about a mile away to the north, and it is only a few feet lower than the 8,786-foot highpoint on the map, so obsessive peakbaggers may want to tag both points to be absolutely sure the summit was attained. The total hike to the summit of Big Pryor Mountain is about 1.2 miles and 1,300 feet of elevation gain on Class 1 trail.
Crater Ice Cave
Formations The back of the cave
From the spot where the trail disappears in the meadow a few feet from the summit ridge, go left for about a hundred yards to a grove of trees and you will find the Crater Ice Cave. This cave has two entrances, one you can walk in from the side and one that is a big hole in the ceiling.
The cave is much bigger than it looks from the entrance, so be sure to bring a headlamp or flashlight so you can crawl down into the back part and see the ice formations. Bring something warm, as the temperature in the back of the cave is very chilly all year round. Another interesting feature is the huge circular holes that were left after huge rocks fell out of the ceiling. There is a cave register in a plastic container on a big rock in the back to your right as you enter the cave.
The main room of Crater Ice Cave
Red Tape and Camping
There are several developed campgrounds in the Pryor Mountains, and tent camping is permitted in the National Forest. For complete regulations and information, visit: Camping in the Pryors
There are no fees to access the sites or roads in the Pryor Mountains.
Big Pryor Mountain
The excellent website done by the Pryors Coalition: Pryor Mountains
Detailed information on the Pryor Mountain Road: Pryor Mountain Road
Dennis Poulin's trip report for Pryor Mountain: Trip report