Mary Mountain–Nez Perce Trail

Mary Mountain–Nez Perce is a 20.2-mile, one-way point-to-point hike across Yellowstone’s Central Plateau, from Mary Mountain East Trailhead (4N1) on the east side of Hayden Valley to Nez Perce Trailhead (OK7) near Lower Geyser Basin. Plan a full day—about 10 hours on foot—and arrange a vehicle transfer or pickup before you start; the trailheads are far apart, and no shuttle was confirmed. The route stays roughly between 7,200 and 8,300 feet, so the distance, altitude and remote setting add up. No pets are allowed.

From Mary Mountain East, the tread rolls over a low hill, eases down toward Alum Creek, then climbs again. Steam from the Sulphur Mountain area can show to the south. The route follows Hayden Valley’s north edge, enters trees briefly, then opens to a broad valley view around six miles in. Small geothermal features and stream crossings punctuate this stretch; one larger seasonal crossing can vary in size. After the overlook, expect roughly 3.5 miles through forest before Mary Lake.

Mary Lake sits near the midpoint, with backcountry thermal areas nearby. The route then drops nearly 1,000 feet over about three miles and levels through meadows alongside Nez Perce Creek toward the west trailhead. Several stream crossings lie along this leg; water levels change, so check conditions and be ready to turn around if a crossing is unsafe. Stay on the established tread around thermal ground; off-trail travel in thermal areas is prohibited.

Grizzlies and bison frequent this country. A hiker was killed by a grizzly on Mary Mountain in Hayden Valley in 2011. The park recommends groups of three or more, staying together, and carrying bear spray immediately accessible. One trip account notes that bison paths and knocked-down markers can make the tread confusing, so bring a map and be able to navigate rather than relying on animal paths. No food or potable water is listed at the trailheads; carry what you need for the day.