In the higher reaches of the mountains is pristine Crystal Lake. There's excellent hiking along interpretive and wildflower trails as well as camping, fossil hunting, and ice-cave exploration. The ice cave is a 6-mi hike from the 28-site campground; June is the best time to see the 30-foot ice pillars formed over the winter. There's a cabin 6 mi from the gate for snowmobilers, cross-country skiers, and snowshoers, but it's closed when the snow is too deep to navigate (which is most of the winter). No motorized boats are allowed on the lake.
Crystal Lake Rd., Montana, 59479 , United States