Mary Mountain Trailhead
This trail takes you through beautiful Hayden Valley and to Mary Lake located in the center of the Grand Loop, an out-and-back distance of approximately 19 miles. The trail initially leads over a small hill and drops slowly in elevation toward Alum Creek while paralleling the treeline before it climbs again to allow a view of rising steam plumes from the Sulphur Mountain area to the south. The trail continues along the northern edge of Hayden Valley, passing briefly through a wooded area before opening to the expanse of Hayden Valley, a favorite gathering place for bison. As you continue, the trail passes a few small geothermal features and through a few small streams. At 4.5 miles into the hike, a larger stream that varies in size depending on the time of the season will require you to find a narrowed place to jump (assuming you still have some good spring in your legs) or to take off your shoes and wade across. Soon after, the trail again begins to gently climb in elevation and at the 6-mile mark reaches the high point on the trail and a beautiful overlook to Hayden Valley. The next 3.5 miles the trail passes through a heavily forested area before reaching Mary Lake. Mary Lake is the headwaters for Nez Perce Creek that flows west from the lake and eventually empties into the Firehole River just behind the Nez Perce Picnic Area near Lower Geyser Basin on the Madison to Old Faithful road section.
Note: If you continue on this trail it becomes the Nez Perce Trail which traverses across the entire length of the Central Plateau all the way to a point between Fountain Flat Drive and Lower Geyser Basin on the Madison to Old Faithful road section, making the total hike 19.8 miles. After leaving Mary Lake, the trail drops nearly 1,000 feet over the next 3 miles and then levels out as it follows Nez Perce Creek through several meadows and requires several stream crossings along the way.