Best Mud Volcano Tours from San Francisco

This Yellowstone National Park landmark rumbled loudly and spewed mud at one time, but an 1872 explosion left the remnants of what the Mud Volcano is today. The U.S. National Park Service notes that it was called "greatest marvel we have yet met with" by Nathaniel Langford in 1870 during the Washburn Expedition. The Mud Volcano Area offers a fascinating collection of mud pots and thermal pools including Sulphur Caldron, Dragon's Mouth Spring, Black Dragon's Caldron, Churning Caldron and Sour Lake.