Upper Geyser Basin
About
Upper Geyser Basin. Yellowstone, as a whole, possesses close to sixty percent of the world's geysers, and the Upper Geyser Basin is home to the largest numbers of this fragile feature found in the park, including the iconic "Old Faithful" geyser. Old Faithful, the world's most famous geyser, has large eruptions occurring an average of about once every eighty minutes, although the timing between each eruption varies by as much as an hour and has been increasing over the years. Rangers are able to predict the geyser's eruptions to within about ten minutes, provided the duration of the previous eruption is known. In addition to Old Faithful, this basin contains an additional 150 geysers within a one square mile area; of this remarkable number, the eruptions of Castle, Grand, Daisy, Riverside, and Old Faithful are predicted regularly by the naturalist staff. In addition to geysers the area is home to numerous hot springs. Boardwalks allow access to the most interesting areas. Do not leave the trails; the surface here is thin and unstable and has a real chance of depositing you in a boiling pool of water if you walk where you're not supposed to.
