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 on the eastern half of Yellowstone National Park. 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 depending on the thermal activity of the specific feature.
There are over a dozen thermal features at the Mud Volcano site, many of which were revealed only as recently as the late 1970s when an earthquake caused the slope to give way and push the thermal activity closer to the surface. The barren area had soil temperatures pushing 200 degrees Fahrenheit and became known as “the cooking hillside.”
Bison frequent the upper areas of the nature walk, so keep an eye out and bring your camera. The bubbling thermal features have some of the strongest smells in the park, which is apparent when you see the way the landscape has been changed with these unique thermal features.