Also, most thermal areas have sulfur deposits lying on the surface. When sulfur catches fire, dangerous, sometimes lethal, fumes are given off. This is a chance we just aren't willing to take. A. Dogs don't seem to recognize the difference between hot and cold water. Dogs have lost their lives diving into hot springs.
Dogs also disturb wildlife and frighten other visitors.
Places like Norris are constantly changing and have hollow areas that may have only a thin layer of rock over them. Boiling water surges just under most of the basins. Most burns received in thermal areas are second and third degree. People have died from falling into thermal features. Although animals usually know where to walk instinctively, they occasionally break through the thin crust.