Sulphur Caldron

This was once a hilltop thermal feature that would hurl mud into the nearby trees during eruptions, but a particularly large eruption blew apart the Mud Volcano, leaving a hot, bubbling mud pool at the base of the hill. Access to the area is via a short loop from the parking lot past the Dragon's Mouth and the Mud Volcano that is handicapped accessible, and a half-mile (0.5 mi) upper loop trail via Sour Lake and the Black Dragon's Caldron that is relatively steep. The rhythmic belching of steam and the flashing tongue of water give the Dragon's Mouth Spring its name, though its activity has decreased notably since December 1994. The Black Dragon's Caldron exploded onto the landscape in 1948, blowing trees out by their roots and covering the surrounding forest with mud. In January 1995, a new feature on the south bank of Mud Geyser became extremely active, covering an area of 20 x and comprised of fumaroles, small pools, and frying-pan type features. The most dramatic features of the Mud Volcano area, including the huge seething mud pot known as the "Gumper", are open to the public only via off-boardwalk ranger-guided walks.

Hayden Valley is one of the best places in the park to view a wide variety of wildlife. It is an excellent place to look for grizzly bears, particularly in the spring and early summer when they may be preying upon newborn bison and elk calves. Large herds of bison may be viewed in the spring, early summer, and during the fall rut, which usually begins late July to early August. Coyotes can almost always be seen in the valley. Bird life is abundant in and along the river. A variety of shore birds may be seen in the mud flats at Alum Creek. A pair of sandhill cranes usually nests at the south end of the valley. Ducks, geese, and American white pelicans cruise the river. The valley is also an excellent place to look for bald eagles and northern harriers.

The LeHardy Rapids are a cascade on the Yellowstone River. Geomorphologically, it is thought that this is the actual spot where the lake ends and the river continues its northward flow. In the spring, many cut-throat trout may be seen here, resting in the shallow pools before expending bursts of energy to leap up the rapids on their way to spawn under Fishing Bridge. A boardwalk, built in 1984, provides access to the area, although it is closed during the spring nesting season to protect this sensitive bird habitat.

The original bridge was built in 1902 as a rough-hewn corduroy log bridge with a slightly different alignment than the current bridge. The existing bridge was built in 1937. The Fishing Bridge was historically a tremendously popular place to fish. Angling from the bridge was quite good, due to the fact that it was a major spawning area for cutthroat trout. However, because of the decline of the cutthroat population (in part, a result of this practice), the bridge was closed to fishing in 1973. Since that time, it has become a popular place to observe fish.

The Fishing Bridge Museum was completed in 1931 and would eventually become a prototype of rustic architecture in parks all over the nation. It was declared a National Historic Landmark in 1987. When automobiles replaced stagecoaches as the main means of transportation through the park, people were no longer accompanied by a guide, so the museum was built as a "Trailside Museum," allowing visitors to obtain information about Yellowstone on their own.

The advent of the auto in the park in 1915 created a great influx of visitors. The need arose for an intermediate style of lodging between the luxury of the Lake Hotel and the rustic accommodations of the tent camps. In 1926, the Lake Lodge (also a Robert Reamer design) was completed, one of four lodges in the park. The park was no longer primarily accessible to only affluent "dudes" or hearty "sagebrushers."