Mud Volcano & Dragon's Mouth Spring
Mud Volcano Area
A strongly acidic thermal area with a strong sulfur smell. Dragon's Mouth Spring blasts out steam and hot water with a roar like a dragon's.
The Mud Volcano area is at the southern end of Hayden Valley. The boardwalk loop is about 1 km and includes a fairly steep section. At the entrance, Dragon's Mouth Spring periodically surges hot water and steam from a cave, accompanied by a low rumbling sound. Mud Volcano was once a mud cone that erupted, but after the 1870s it collapsed into a boiling mud pool. Sulphur Caldron is one of the most acidic hot springs in the park. Bison often lie nearby, so keep your distance. The air carries a strong smell of hydrogen sulfide, so do not linger.
Opening hours
Open all day (road open about May–Nov)
Nearby sights
- Hayden Valley
- Grand Canyon of the Yellowstone
- Mount Washburn
- Yellowstone Lake
- West Thumb Geyser Basin
- Tower Fall
- Norris Geyser Basin
- Artists' Paintpots