Geyser
Yellowstone is the largest geyser locale, containing thousands of hot springs, and approximately 300 to 500 geysers. It is home to half of the world's total number of geysers in its nine geyser basins. It is located mostly in Wyoming, USA, with small portions in Montana and Idaho. Yellowstone includes the world's tallest active geyser (Steamboat Geyser in Norris Geyser Basin), as well as the renowned Old Faithful Geyser, Beehive Geyser, Giantess Geyser, Lion Geyser, Plume Geyser, Aurum Geyser, Castle Geyser, Sawmill Geyser, Grand Geyser, Oblong Geyser, Giant Geyser, Daisy Geyser, Grotto Geyser, the Fan & Mortar Geysers, & the Riverside Geyser, all in the Upper Geyser Basin which alone contains nearly 180 geysers.
Great Fountain Geyser
The geyser erupts every 9 to 15 hours. Great Fountain's maximum height ranges from about to over . Its duration is usually about one hour but durations of over two hours have been seen. The duration of an eruption affects the interval that will elapse before the next eruption, so that if the duration of an eruption is recorded, the time of the following eruption can be predicted to a precision of about two hours. The prediction can be refined, to plus or minus 15 minutes or so, through observation of overflow from the crater during the period between eruptions. While this pattern of behavior is observed most of the time, there are occasional episodes of so-called "wild-phase" activity during which the eruptions are of greatly extended duration and intervals between eruptions may be as long as three days. The geyser is then unpredictable until wild-phase activity ceases and more normal eruptions resume.