Fountain Geyser, Fountain geyser in Lower Geyser Basin of Yellowstone National Park, Wyoming, United States.

Fountain Geyser is a fountain-type geyser in the Lower Geyser Basin of Yellowstone National Park, the dominant member of a group of geysers at the Fountain Paint Pots thermal area. Its eruptions send jets up to 80 feet (24 m) or more, with most eruptions containing at least a few bursts reaching 40 to 50 feet. Nearby Morning Geyser is larger but inactive most years.

Fountain Geyser is the dominant member of the geyser group at the Fountain Paint Pots thermal area in Lower Geyser Basin, Yellowstone National Park. Nearby Morning Geyser erupts from a vent close to Fountain's and is larger, but it is inactive most years while Fountain is usually active. The two are distinct features, and Fountain should not be confused with the larger Great Fountain Geyser near the Firehole Lake road.

The name comes from the fountain-like jets of water that shoot into the air. Visitors can see the colored mineral deposits around the pool, created by the hot mineral-rich water.

Fountain Geyser erupts at intervals of about 4.5 to 6 hours, sometimes 11 to 12 hours, and each eruption lasts around 30 minutes. Plan for a wait of several hours and watch for the start of overflow at the pool before the bursts begin.

Fountain Geyser usually erupts about every 4.5 to 6 hours, but intervals of 11 to 12 hours occur. In a rare "wild-phase" eruption the jet height drops sharply while the eruption can last as long as two weeks. It should not be confused with the larger Great Fountain Geyser nearby.