Sulphur Spring (also known as Crater Hills Geyser), is a geyser in Yellowstone National Park. A geyser is a Hot spring characterized by intermittent discharge of water ejected turbulently and accomplished by a vapour phase
It is located in the Crater Hills area of Hayden Valley located about 1 mile west of the Grand Loop Road.
References
From "Yellowstone Place Names" By Lee H. Whittlesey 2nd Edition 1999