Solitary Geyser is a fountain-type geyser

Geyser

A geyser is a spring characterized by intermittent discharge of water ejected turbulently and accompanied by a vapour phase . The word geyser comes from Geysir, the name of an erupting spring at Haukadalur, Iceland; that name, in turn, comes from the Icelandic verb geysa, "to gush", the verb...

 in Yellowstone National Park

Yellowstone National Park

Yellowstone National Park, established by the U.S. Congress and signed into law by President Ulysses S. Grant on March 1, 1872, is a national park located primarily in the U.S. state of Wyoming, although it also extends into Montana and Idaho...

, located above the Upper Geyser Basin. Eruptions last about a minute and are four to eight minutes apart; most eruptions are less than six feet (2 m) in height. Solitary Geyser is accessible via the Observation Point loop trail behind Old Faithful.

Originally this geyser was a hot spring

Hot spring

A hot spring is a spring that is produced by the emergence of geothermally heated groundwater from the Earth's crust. There are geothermal hot springs in many locations all over the crust of the earth.-Definitions:...

known as Solitary Spring, which did not erupt. When water was diverted to a swimming pool, the water level was lowered sufficiently to cause eruptions. Since then the diversion of water has been stopped and the water has returned to its previous level, but eruptions continue.