Union Falls Trail

HARD 27 reviews
#24 of 204 trails in

Union Falls Trail is a 15.6 mile heavily trafficked out and back trail located near Yellowstone National Park, Wyoming that features a waterfall and is rated as difficult. The trail offers a number of activity options and is best used from May until September. Horses are also able to use this trail.

15.6 miles
1932 feet
Out & Back




horseback riding

trail running





no dogs

Union Falls is the second highest waterfall in Yellowstone, towering above at 260 feet. The falls is very unique in shape and serves those bringing cameras very well. Union Falls is located in the southwest section of Yellowstone. Formed as two creeks come together and fall over 250 feet. Union Falls is very impressive and worth the hike to get to.

4 months ago

great trail.... away from all of the people in YNP... bring deet if hiking in summer.. tons of mosquitoes and flies.. a little difficult when hitchhiking to the trailhead... I hitched from old faithful to the start of the dirt road... then off and on until I got to the trailhead... I think I spent more time hitchhiking to the trailhead than on the trail! haha .. fun trail.. wide river ford at the beginning..

4 months ago

I have always come in from Fish Lake. This trail features three river crossings, which for me adds to the fun, and skips the elevation gain of the Grassy Lake trail. About the same total distance. Hardly ever meet anyone on this trail.

5 months ago

Great hike, came back in the dark, couple creek crossings, one big one . The water at Ouzel Pool was amazing. Heading back before the season ends. Falls was beautiful, the pool was the best.

5 months ago

The scenery is worth every step. We started at Cascade trail instead of Grassy Lake and did the Terrace Falls trail then came back to the trail sign and headed up Union Falls. Terrace Falls followed the river so the scenery was completely different than Union Falls. This made it a total of about 19.5 miles. Bring a swim suit and plan on swimming in the warm spring just a .3 mile detour to the left before Union Falls. At Unions Falls there is a trail that will take you down to the falls so you can get right next to it. Worth every step. 1 major river crossing. Heading back the cold water felt AMAZING on sore muscles. Even though this is not a steep trail plan on it taking you twice as long to get back because it is so long.

5 months ago

I would rate this trail moderate, not hard as in the description.

Coming from the Ashton side, there's about 25 miles on dirt roads, and it will take some time to get there. About one mile in, you will need to ford the Fall River. Depending on the time of year, the river can be anywhere from knee deep to thigh deep. As far as water crossings go, this one isn't bad at all. Trekking poles help a lot.

Beyond that, the trail is pretty straightforward, kind of rolling up and down the hills. There's generally plenty of shade, and plenty of spots to filter water.

The falls, located about 7.5 miles from the trailhead, are worth the effort. This is the second largest waterfall in Yellowstone, and is named for the two streams that converge at the waterfall.

Expect mosquitoes and horseflies from late June through early September (bring plenty of bug spray). Bear spray is also recommended.

5 months ago

Awesome! The hike back is harder than the hike in. Easily one of my favorite hikes!

Tuesday, September 20, 2016

Just an FYI... the road to this trailhead is now closed for the season :)

Friday, September 09, 2016

This hike is awesome! We did it in early September and the water was low and there were NO bugs. Going to scout pool is a must. It took us about 3 hours each way. Definitely worth the hike

Tuesday, September 06, 2016

beautiful falls but not much to look at til you get there

Tuesday, July 26, 2016

Lots of creek crossings! Great hike!!!

Monday, July 13, 2015

Long hike (16.5 miles) from cascade creek (include the side trip to the pool) but very rewarding. Gorgeous views of the unions fall and a delightful hydrotherapy session in Ouzel pool (the water is lukewarm, not cold, thanks to a nearby hot spring).

Wednesday, June 11, 2014

Completed this trail in early June. The length of the hike was not nearly as challenging as fording the river, which was running high and fast. There was still snow on quite a bit of the trail, and the mosquitoes were certainly present. However, the falls were incredible and definitely worth the work it took to get there. If you go in early June, skip the side trip to Scout Pool. There was still too much runoff to allow the pool to heat up to comfortable temperatures... unless you like a cold bath. :) Very much looking forward to hiking this on again later in the year.

Wednesday, May 15, 2013

This is a beautiful, though difficult, hike. The waterfall is worth the trip alone but the pools are basically heaven on earth. The pool is just like the firehole river without the crowds.

Tuesday, October 16, 2012

First a note: this place is at least an hour from Moose, unlike the description says. It is just inside the southern boundary of Yellowstone, west of Flagg Ranch, near Grassy Lake. Make sure you have good directions, the appropriate topo maps, and the skills to use them before you do any backcountry hiking in Yellowstone. We hiked from the Reservoir, crossed the river, did the long easy climb and steep descent down aptly named Cardiac Ridge. Look for ruts in the rocks carved by the wheels of pioneer wagons. This route passes through nice lodgepole forest, includes one serious river crossing that may not be passable early in the summer and another stream crossing. There is just the one major climb and descent--easy on the way in and a butt-kicker on the way out. The payoff is arguably the most spectacular backcountry waterfall in North America--a bridal veil fall that is taller than Niagara. We have never seen other people at the falls--though we did catch a weird glimpse of a naked couple skipping through the meadow a few hundred yards from our campsite. Literally skipping, hand in hand. Look for the hot spring-fed creek just north of the canyon. It's a great swimming hole.

Monday, August 06, 2012

we have rode horses in there many times great easy ride 19 miles round trip worth every step! boy scouts in there wednesdays and thursdays be prepared for a crowd those days. people from all over the world you will meet! Pack bear spray. horses need valid coggins testing and no dogs allowed cause your on jellystone national park! we get there from the ashton flagg ranch road!

Saturday, July 14, 2012

Just hiked from fish lake trail head to union falls and back. Made for a long day but Great hike. The warm spring fed scout pool was worth it and the falls were breath taking too. Could have done without all the bugs. Horseflies the size of small children.

Thursday, June 07, 2012

A long but rewarding trail. Union falls is spectacular. Don't miss a swim in the hot springs slightly off the trail near the falls

Friday, October 07, 2011

Union Falls is stunning! The hike is pretty easy without much elevation gain and the trail is in great shape. Only 1 water crossing where getting wet is impossible to avoid but it's not difficult. We went in the fall and the changing colors were great!

Monday, May 23, 2011

Greatest Waterfall View EVER!!!!!

5 months ago

Load More