Access to Old Faithfull Geyser Thermal Area Old Faithful erupts more frequently than any of the other big geysers, although it is not the largest or most regular geyser in the park. Its average interval between eruptions is about 91 minutes, varying from 65 - 92 minutes. An eruption lasts 1 1/2 to 5 minutes, expels 3,700 - 8,400 gallons (14,000 - 32,000 liters) of boiling water, and reaches heights of 106 - 184 feet (30 - 55m). It was named for its consistent performance by members of the Washburn Expedition in 1870. Although its average interval has lengthened through the years (due to earthquakes and vandalism), Old Faithful is still as spectacular and predictable as it was a century ago. With half of the earth’s geothermal features, Yellowstone holds the planet’s most diverse and intact collection of geysers, hot springs, mudpots, and fumaroles. Its more than 300 geysers make up two thirds of all those found on earth.