Generally considered to be the first national park in the world, Yellowstone National Park is significant in size, covering parts of Wyoming, Montana, and Idaho, and acts as the largest remaining nearly-intact ecosystems.  The park is able to support many types of wildlife including Grizzly bears, cougars, wolves, mountain goats, free-ranging herds of bison and elk, as well as many types of birds and fish, because of the diversity of habitats.  Forests and grasslands dominate some areas of the park, while others offer the completely different experience of mountain ranges, lakes, and rolling prairies.  Some of the park's most unique features are the geysers and hydrothermal features.  In fact, Yellowstone is home to over half of the world's features like these.  This is due to the entire park being centered over the Yellowstone Caldera, the largest super volcano on the continent.