Union Falls

Union Falls is a waterfall in Yellowstone National Park where water drops 250 feet (76 m) down the mountainside in wide, curtain-like sheets. The cascade originates from Mountain Ash Creek and creates a powerful display as it falls against the exposed rock face.

A survey team led by Arnold Hague documented and named this waterfall between 1884 and 1886 during their geological exploration of Yellowstone. The team noted how the water converges at the meeting point of two creeks.

Naturalists and photographers travel to this remote section of Yellowstone National Park to document the second-highest permanent waterfall in the park.

The hike to this waterfall starts at Grassy Lake Trailhead and covers about 16 miles total distance through thick forest and backcountry. Expect river crossings along the way and bring adequate supplies and proper hiking gear for the remote terrain.

Near the waterfall sits Ouzel Pool, a natural swimming hole that stays warm because of geothermal heat rising from below the surface. This warm water creates an unusual chance for visitors to swim in this remote location.

Location: Wyoming

GPS coordinates: 44.19278,-110.87083

Latest update: December 13, 2025 12:21