Continuing to the west, pass through a grassy meadow frequented by grizzlies as the trail climbs upward at a moderate grade. After winding through woods dotted with Douglas firs and aspens, the trail flattens out around mile 2.1 and crosses into a broad, grassy field, offering superb panoramas of Mammoth Hot Springs, the surrounding mountains, and a pine-blanketed countryside.
From the grassy plateau, it's an easy downhill to the Orange Spring Mound at mile 3.9. This 20-foot-high feature, which owes its signature orange hue to microbial bacteria, has grown so large that it actually hides the spring that feeds it. Less than a half mile further, the trail visits the Narrow Gauge Terrace where a set of terraced, travertine pools emit steam and vapors. Break out your camera to document this striking geothermal feature before heading back to Waypoint 4 and turning right to complete the loop.
MORE PARK INFO: Yellowstone National Park, (307) 344-7381; nps.gov/yell/.
-Mapped by Jeff Chow
Trailhead: From Tower Junction, head northwest on Grand Loop Rd. for 18.1 miles. Turn left at Grand Loop Rd. and head south. Go 0.3 mile to trailhead parking.