Northwest of St. Mary from Many Glacier in Glacier National Park, the 27 mile Ptarmign Tunnel loop is considered to be one of the parks best backpack trips. This three-day hiking route starts at Many Glacier and heads up the Wilbur Creek drainage and over to Ptarmigan Lake. Then, switchback up to Ptarmigan Tunnel and on through heading north. Drop down to the junction with Red Gap Pass Trail. Turn left heading northwest on up the Belly River and camp up at Elizabeth Lake. Return on the Red Gap Pass Trail over Red Gap and down along the Kennedy Creek Valley. Another good campsite is at Poia Lake. Climb up to Swiftcurrent Ridge Lake and finally back down to Many Glacier.
Overall, Ptarmigan Tunnel is the 12th most popular hiking trail of all 19 hikes in Montana.