A sublime backcountry swimming hole awaits you at the end of this 15.8-mile out-and-back to Union Falls. Start by heading north for 0.3 mile to cross the park’s southern border. Stay right at the Terraced Falls trail junction, ford Cascade Creek after half a mile, then drop into willow-choked marshland near the Mountain Ash Trail junction and cross the 50-foot-wide Falls River. Stay left on the trail and climb among conifers, then descend along an 1880s wagon road to two easy fords of Proposition Creek at 4.9 miles. Double-back to the northeast at the junction above Mountain Ash Creek, and cross the footbridge near two good campsites. Head left at the fork to the swimming hole, or go right to take in some spectacular views of 250-foot Union Falls.
Info: Park news and trail updates: ynp.blogspot.com.
Backcountry office: (307) 344-2163; www.nps.gov/yell.
-Hike provided by Andrew Dean Nystrom, author of Top Trails: Yellowstone & Grand Teton National Parks (Wilderness Press).