• An aerial view of Old Faithful erupting taken from Observation Point with the Old Faithful Inn to the side.

    Yellowstone

    National Park ID,MT,WY

Fumaroles and How They Work

A fumarole emits a jet of hot steam in Porcelain Basin.

Fumaroles, or steam vents, are the hottest hydrothermal features in the park. They have so little water that it all flashes into steam before reaching the surface. At places like Roaring Mountain, the result is a lot of hissing of steam and gases.

Black Growler Steam Vent

Norris Geyser Basin

Did You Know?

Summer Crowd at Old Faithful.

At peak summer levels, 3,500 employees work for Yellowstone National Park concessioners and about 800 work for the National Park Service.