St Mary Lake is a 20-mile out-and-back foot trail in Glacier National Park, Montana. It climbs 969 ft to a high point of 4,834 ft. Difficulty: strenuous, from the NPS hiking-rating formula.

Open St Mary Lake on Trailbound's interactive map to see the full route, the elevation profile, today's forecast and any park alerts for Glacier. Glacier has permits or reservations for some areas: see the Glacier page for what's needed.