Sour Lake in Yellowstone National Park

Mud Volcano Trail in Yellowstone National Park

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The Mud Volcano Trail in Yellowstone National Park is one of many boardwalk trails in Yellowstone that wind their way through a myriad of geological features.  What makes the Mud Volcano Trail unique and worth a stop is the variety of sights available on such a short walk.

From mud pots to fumaroles to the placid looking Sour Lake (that you do not want to swim in!), the high concentration of attractions makes this place something that you’ll want to make sure you visit during your trip to Yellowstone National Park!


  • Difficulty: Easy
  • Distance: 0.8 miles (round-trip)
  • Trail: Loop
  • Elevation gain: 124 feet
  • Peak elevation reached: 7,879 feet
  • Best time of year to hike: Spring through fall
  • To beat the crowds: Arrive before 9:00 am or after 3:30 pm
  • Footwear: Sneakers
  • Watch out for: Mosquitoes, bears, bison, sun exposure
  • Restrooms: Located at the trailhead, but not on the trail
  • Pets: Not allowed
  • Time needed: 45 minutes



yellowstone national park itinerary


We cover Mud Volcano and over 20 other hikes, things to do in our itinerary for Yellowstone National Park.  This is a downloadable guide that covers what to pack, where to stay, what to reserve ahead of time and what to see nearby Yellowstone.  There is so much to do in Yellowstone National Park that it can be overwhelming, and our guide helps take the guesswork out of planning!


Mud Volcano area map in Yellowstone National Park

The Mud Volcano Trail is located in the Hayden Valley of Yellowstone and is situated on Grand Loop Road between Fishing Bridge (home of Yellowstone Lake) and Canyon Village (home of Grand Canyon of the Yellowstone).

The parking area for the trail is on the western side of Grand Loop Road.  The parking lot has nearly 70 spots. Seeing as though the trail takes only about 30 minutes for most visitors, parking spots will open at a rate of about 2 every minute.  So, if you get to the lot and see a ton of cars parked, just be patient and a spot will open up quickly. Still, you need to realize that this is a popular spot, and crowds (including buses) should be expected.

There are restrooms available on the south end of the parking lot, but there are no restrooms on the trail.  However, the wait for the restrooms may be a bigger concern than trying to get a parking spot!


Mud Volcano trailmap in Yellowstone National Park

There are two options when hiking the Mud Volcano Trail.  For those who are short on time or need a trail accessible to wheelchairs, the small loop that starts on the north side of the parking lot goes by both the Mud Volcano and Dragon’s Mouth Spring.  Those who can climb a total elevation gain of 124 feet (with a combination of stairs and inclined pavement) should take the entire loop and not miss out on the other features that this hike offers.

Though it was raining lightly when we visited the park, we decided to walk the entire loop so we could see everything.  The trailhead sign recommends heading in the clockwise direction to have a less steep climb. For some reason we chose to hike in the counterclockwise direction and it was more than doable for our family.  As you’ll see later, the incline was the least of our worries on this hike!

Like so many other sights in Yellowstone, the “trail” is actually an elevated boardwalk for much of the loop.

Mud Volcano trail in Yellowstone National Park

Shortly after beginning the walk, the trail comes to Dragon’s Mouth Spring.  Dragon’s Mouth Spring is a cave with gases and near boiling water that make booming sounds against the top of the cave.  The cave appears to be breathing with water coming in and out of the cave like waves against a rocky coastline. Our family thought this was one of the coolest features we saw in the park and stood watching it for quite some time.

Dragons mouth spring in Yellowstone National Park

Dragons mouth spring in Yellowstone National Park

Past Dragon’s Mouth Spring, the boardwalk leads to the trail’s namesake, Mud Volcano.  When first discovered in 1871, Mud Volcano was a fairly violent mud spring. As the years have passed, the activity has subsided (except for a brief time in 1979).  Though surely not quite as impressive as what the initial explorers found, it is definitely worth checking out.

Mud volcano in Yellowstone National Park

After passing by the Mud Volcano, the boardwalk splits.  This is where those looking for a short walk will take a left to return back to the parking lot.  For those wanting to continue on the full loop (which is recommended), a right turn will lead you onto the paved trail and uphill toward Sour Lake.



The trailhead signs warn of bison that frequent the area, and it was here that we passed by the first of three bison we saw on the trail.  It’s important to remember that Yellowstone is full of wild animals, and bison are some of the most dangerous in the park.

bison in Yellowstone National Park

After climbing a few flights of stairs, the boardwalk continues to Sour Lake, which is the furthest spot from the parking lot.  Sour Lake surprised us with its beauty and stillness. Though seemingly harmless, Sour Lake is far from it. The “water” in the lake has a super low pH, making it as potent as battery acid.

sour lake in Yellowstone National Park

Just past Sour Lake is a small offshoot of the trail that leads to Black Dragon’s Caldron.  Black Dragon’s Caldron was not part of the park until 1948, when underground activity shifted some of the thermal activity from Sour Lake to form Black Dragon’s Caldron.  

Black Dragons Caldron

After meeting back up with the main trail and continuing counterclockwise, the trail passes by Churning Caldron.  While the smell of sulfur permeates the atmosphere all around Yellowstone, it seemed to be strongest outside of this geothermal feature (so a few of us couldn’t stay long!).  This was one of the more active features on the Mud Volcano Trail, continuously bubbling.

Churning Caldron in Yellowstone National Park

After the Churning Caldron, the trail passes through the “Cooking Hillside.”  This lush landscape was dotted with small fumaroles and ground that was far from inviting, though it was clear that the bison knew how to navigate the area based on signs they left behind.  We’ll spare the photos of the bison sign!

Cooking hillside in Yellowstone National Park

As the trail ends, it descends quickly to the parking lot.  It was here that we had to pause due to several bison that were blocking the trail.  We even saw one push a tree over right near the parking lot! After being patient and waiting, we decided to return the same way we came, doing the entire loop again in the clockwise direction.  

We did see some other tourists getting way too close to the bison here-later on that day we read online that a couple (in their 70’s) on their honeymoon had to be rescued (with one of them having to be airlifted) after being thrown in the air by one of the bison on this trail.


  • We can’t emphasize enough the importance to be aware of the bison while on this trail.  While physical encounters are rare, they frequently end up with hikers getting injured, and sometimes with life-threatening injuries.  Be careful and show respect for these amazing (and huge!) animals.
  • Nearby the Mud Volcano Trail (just 0.1-mile north) is Sulphur Caldron.  This very active hot spring spews gases with yellow roaring waters. It is a quick drive from Mud Volcano and with a few minutes.

yellowstone national park itinerary


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About Just Go Travel Studios

We are Amy & Pete Brahan. Very simply, we are passionate about our National Parks and Public Lands and explore them with our three kids whenever we can.

As much as we enjoy traveling, we also love sharing our knowledge and helping others create everlasting memories through our custom-made travel posters, downloadable travel itineraries and detailed blog articles.

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