Backpack to Union Falls and Scout Pool, Yellowstone NP

16 miles 950 ft gain  - Out-and-Back Trail

Added by Allie Morris

A Yellowstone hidden gem: sleep under the stars, stand under the second highest waterfall in the park, and soak in secluded hot springs.

Of a summer spent living in Yellowstone, and many overnight trips in the park, the trek to Union Falls and Scout Pool ranked at the top of my list. (Many of my fellow gas station employees agreed!) The hike itself is nothing spectacular, but takes you to two of the most beautiful places in the park that most people will never see (or even hear about). If you have an extra day or two in Yellowstone, and want a crazy adventure to tell your friends about, this is it!

The hike begins outside of Yellowstone's South entrance, but you will enter the park again after a few minutes of hiking. To reach the trailhead, drive South on Highway 191 past Lewis Lake, and take a right at Ashton Flagg-Ranch Road. This road is pretty rough, so 4-Wheel drive is recommended (though I took my little Honda Fit and she did just fine! ... with a few scratches). Drive until you come to a giant bridge on your left. Instead of driving across, you should see a steep hill going down to the right. If you have any doubts if your car can make it back up, just park at the top of the hill and hike down from there (like we did).

The first mile or so is relatively flat. When we did this trip we didn't arrive at the trailhead until 9:30 at night, and hiked this section in the dark. After a mile of walking, you will approach a wide river that you will need to cross. The river was pretty high when we went in late June (came up to our upper thighs and waists), but was crossable, even late at night. The three of us crossed linking arms in a tripod formation. Make sure you check the water levels with the backcountry office before heading out.

9F2 is the closest campsite, right after the ford, and comes complete with a fire pit, bear hang, great views of the stars, and background soundtrack of the rushing river. Other campsites (9U4 and 9U5) are farther down the trail and are great options to camp closer to the falls if you can get an earlier start than we did!

The first morning, wake up, build a fire, drink a cup of joe and lather yourself with bug spray and sunscreen (you will need it). Note** The mosquitoes are killer and WILL bite through your yoga pants and any other tight or thin clothing.

From campsite 9F2, the trail begins going uphill, but quickly becomes a descent through forest and then through an area of exposed rock. You will cross multiple small streams that may force you to take your shoes off depending on the season, but nothing too intense.

Hike past campsites 9U4 and 9U5 until you reach a large hitching post area and bear hang. From here, keep right and hike the final half mile to Union Falls. Once at the top, you'll get a breathtaking view overlooking the falls, but don't stop there! If you are down for a little more adventure, climb down the side of the hill and follow the trail (that is washed away in parts) to the foot of the falls. The temperature drops as you get closer, and a rain jacket is great at protecting you from the cold spray! You can walk right under the waterfall, but be careful. The water is powerful, and the ground extremely slippery.

After you have spent some time enjoying the beauty of the falls, hike back to the junction at the hitching post. Instead of heading back the way you came, veer right and follow the trail half a mile towards the river. You'll come to a small waterfall and surrounding rocks that create Scout Pool, the perfect place for swimming and soaking. The water here is warmed by geothermal hot springs, and is named after the Boy Scout camp which is nearby. When we did the hike we ran into a group of Boy Scouts at the falls, but had the pool all to ourselves.

Dry off, reapply bug spray, and follow the trail past the hitching post back the way you came. If you are hungry after the hike, make sure to stop and grab a burger at Flagg Ranch Headwaters Lodge. You will pass the restaurant on your way out to the main road.

**This hike can also be done in one long day (and ranks as one of the best day hikes in Yellowstone), but get on the trail as early as possible so you can spend time exploring the falls and relaxing in Scout Pool!

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Hot Springs
Swimming Hole


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🥇Top Contributor

over 3 years ago

Awesome Hike

Love this waterfall and the hike up to it. It's a good long hike, but isn't too bad until the last stretch up the mountain. 👍🏻

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