Just 45 minutes south of Big Sky is the West Entrance to Yellowstone National Park. Montana may be the last best place, but Yellowstone National Park is a one-of-a- kind place, for reasons that are geological and ecological. Geologically speaking, Yellowstone is one of the wonders of the world because of its geysers. The strict definition of a geyser is a hot spring that displays intermittent, turbulent eruptions of water vapor. By far the largest geyser field on Earth, Yellowstone contains over five hundred geysers - more than exist in the entire rest of the world. Animals such as grizzly bear, mountain lion, wolverine, elk and pronghorn antelope have survived here since prehistoric times. Perhaps the most magnificent sight of all is the enormous bison herd a throwback to the original vistas of the North American continent, before the first white man arrived from the east.