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Mud Volcano Trail

RECOMMENDED ROUTE
Easy/Intermediate Easy/Intermediate
 4.4 (31)
  1. Areas
  2. WY
  3. …Northwestern Wyoming
  4. …Yellowstone National Park
  5. Fishing Bridge
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“A short loop leads past some of Yellowstone's most interesting mudpots, springs, and fumaroles. ”

Tom Carter
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0.8

Miles

1.4

KM

Loop

7,870' 2,399 m

High

7,757' 2,364 m

Low

119' 36 m

Up

115' 35 m

Down

5%

Avg Grade (3°)

18%

Max Grade (10°)

Dogs No Dogs

Features Geological Significance · Hot Spring · Wildlife

Family Friendly A short loop with great views of mudpots, springs, and fumaroles.

Geyser basin boardwalks protect you and preserve delicate formations. You must stay on boardwalks. Pools may be near or above the boiling temperature and can cause severe, possibly even fatal, burns. You may also see bison on this trail; try to stay at least 25 yards away. Bison are always dangerous, but by August, rutting season begins, and the bulls become extra aggressive.

Overview

The interesting mud pots and fumaroles of the Mud Volcano Area make for an excellent short walk as a stop between Yellowstone Lake and Grand Canyon of Yellowstone. Fumaroles are steam vents that leech sulfuric acid into the surrounding rock and boil away the ground water. This forms a feedback loop that breaks the rock into a sticky clay that bubbles almost constantly.

Description

The .8-mile loop climbs 100 feet uphill and leads past some of Yellowstone's most interesting mudpots, springs, and fumaroles (steam vents). The lower loop to Dragon's Mouth and the Mud Volcano is wheelchair accessible. The features in the Mud Volcano Area are among the park's most acidic. Hydrogen sulfide gas, with its odor of rotten eggs, makes this one of the smelliest places in Yellowstone.

Begin your adventure at the far right end of the parking area. Follow the boardwalk to turbulent, splashing Dragon's Mouth Spring. The rhythmic belching of steam and the flashing tongue of water give the Dragon's Mouth its name. Although there is much activity here, notice that very little water leaves the pool through its runoff outlet.

Next up is the Mud Volcano, and especially large mud pot formation that used to stand much higher, before an especially large eruption blew up the mud cone. It still bubbles and steams with interesting noises and smells.

From Mud Volcano the trail begins to climb up the hill to Sour Lake and Black Dragon's Caldron. Along the way you'll pass Grizzly Fumarole. The hiss and roar of a fumarole comes from gases - steam, carbon dioxide, and a little hydrogen sulfide - rushing from the earth through the vent.

Sour Lake is just that, a thermally-fed small lake. Just beyond it is Black Dragon's Caldron. It exploded onto the landscape in 1948, blowing trees out by their roots and covering the surrounding forest with mud. The large turbulent stirring at one end of the Caldron gives one the sense that the Black Dragon itself might rear its head at any time.

The trail then loops back down the hill, along the way passing Churning Caldron and Sizzling Spring. The slope below Sizzling Basin, once covered with green grass and trees, became a barren landscape of fallen trees now known as "the cooking hillside." Near the bottom of the hill you'll see the area known as Mud Geyser, a large muddy pool to the right, that for 30 years in the 1800s erupted to heights of 20 to 50 feet.

Thanks to guidebook author, Tom Carter, for sharing this trail description. To learn more about visiting Yellowstone, check out his book, Day Hiking Yellowstone.

Flora & Fauna

Bison, commonly (though incorrectly) called buffalo, are often seen in the Mud Volcano Area. Bulls often weigh a ton or more and are the largest land mammals in North America. Both the male and female have horns made of compacted hair around a bony core. Horns are permanent features and are not shed annually like antlers. At one time an estimated 60 million bison roamed the American West. By 1890 they were nearly exterminated. Today, Yellowstone is the only place in the U.S. where wild bison have persisted since the first Europeans arrived in the new world.

History & Background

The 1870 Washburn Expedition described Mud Volcano as "greatest marvel we have yet met with." At that time, Mud Volcano had a cone-shaped mud deposit (like a volcano) that covered the feature and gave off booming sounds that could be heard a mile away "like the discharge of artillery." They further reported that it threw mud immense distances and that they found it in the tops of trees 100 feet high and 200 feet away. By 1872 a thermal explosion had blown the mud cone away to reveal what we see today. Although the Mud Volcano can no longer be heard from a mile away nor does it throw mud hundreds of feet in the air, the area is still intriguing.

Contacts

Local Club: Yellowstone Forever

Jun 22, 2025: Star Parties & Solar Observations with Lynn Powers

Jun 16, 2025: Naturalist Notes: Nursery of the Wild

Jun 11, 2025: Winter’s Magic Awaits in Yellowstone

Land Manager: National Park Service - Yellowstone National Park

Shared By:

Tom Carter
Full Details

Trail Ratings

  4.4 from 31 votes

#1

in Fishing Bridge

#492

Overall
  4.4 from 31 votes
5 Star
45%
4 Star
45%
3 Star
10%
2 Star
0%
1 Star
0%
Recommended Route Rankings

#1

in Fishing Bridge

#23

in Wyoming

#492

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Photos

Dragon's Mouth Spring
Sep 10, 2015 near Lake Vi…, WY
Hey there, Bison!
Sep 10, 2015 near Lake Vi…, WY
Cooking hillside
Jul 28, 2017 near Lake Vi…, WY
A well-maintained path.
Sep 10, 2015 near Lake Vi…, WY
rainbows
May 15, 2019 near Lake Vi…, WY
Visitors get a bit close as a large bison approaches.
Apr 25, 2016 near Lake Vi…, WY

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All Clear 64 days ago
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