In Depth - Predicting Old Faithful

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4 minutes, 41 seconds

Old Faithful was once called “Eternity’s Timepiece” because of the regularity of its eruptions. However, this geyser never erupted at exact hourly intervals as many believe. Ranger Darlene Bos explains how we predict eruptions for this popular geyser. Additional filming by David Restivo and Jay Elhard.

Silhouette of a geyser erupting and the underlying plumbing system.
Predict Old Faithful

Calculate your own prediction for Old Faithful's next eruption.

Eruption plume of Great Fountain Geyser.
Hydrothermal Features

More than 10,000 hydrothermal features are found here, of which more than 500 are geysers.

A rainbow stands out as a geyser erupts.
Current Geyser Activity

Get the latest geyser eruption predictions.

A tall geyser erupts in the afternoon sun.
Old Faithful FAQs

Is Old Faithful slowing down. Learn that and more.

Two people watch a geyser erupt under a star-filled night sky.
In Depth: Geysers

Learn about the mechanics of geysers, their role in the park's history and what they teach us about the world in which we live.

Last updated: September 13, 2022

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