Spasmodic Geyser, Geyser in Upper Geyser Basin, Yellowstone National Park, Wyoming, United States.

Spasmodic Geyser is a fountain-type geyser in the Upper Geyser Basin of Yellowstone National Park. Its two craters throw water up to 15 feet (4.6 m) high, while roughly 20 smaller vents spout from a few inches to ten feet. Eruptions are irregular, most falling in the 1–3 hour range, and the water is about 92 °C (198 °F).

Spasmodic Geyser was named by A.C. Peale of the 1878 Hayden survey team, who chose the name for its erratic eruptions. The geyser sits in the Upper Geyser Basin of Yellowstone National Park, where its irregular intervals, mostly one to three hours, drew the attention of early survey geologists.

A.C. Peale of the 1878 Hayden survey named it for its erratic eruptions, which occur at irregular intervals, mostly one to three hours apart. The geyser is linked underground to the smaller Penta Geyser: when Penta erupts, Spasmodic goes quiet, and Spasmodic's activity usually comes before eruptions of Sawmill and Penta.

You can watch eruptions from designated boardwalks built around the geyser. Activity varies considerably, so plan to spend one to three hours waiting between eruptions.

Spasmodic Geyser's activity usually comes before eruptions of Sawmill Geyser and Penta Geyser, so watchers use it as an early signal. The two craters throw water up to 15 feet, while roughly 20 smaller vents spout from a few inches to ten feet.