Video of the Sulphur Springs, a backcountry thermal area in the Crater Hills, near Hayden Valley in Yellowstone National Park; bison on the mud flats to the south, then a selection of the pools and mud pots of the springs, including two of the named features, Turbid Blue Mud Spring and Crater Hills Geyser. This latter is the most active spring in the area, erupting constantly to heights of five feet or more. (mp4; 2:08 min; 40 mb)