Fan Geyser

Overview

Fan Geyser sits in the Upper Geyser Basin, the park’s densest collection of thermal features centered around Old Faithful. It’s not a constant performer, but when Fan goes, it throws powerful, angled jets in a broad spray pattern that looks exactly like its name. The real jackpot is when Fan pairs up with neighboring Mortar Geyser—together they produce a loud, long, high-energy eruption sequence that’s one of the basin’s most thrilling sights.

What You’ll See

Expect fan-shaped bursts soaring roughly 60–80 feet and a sustained, multi-minute display; some events can continue on and off for much longer. Intervals are irregular—think hours between shows and sometimes much longer—so this is a patience play rather than a quick stop.

How to Catch It

Start your day at the Old Faithful Visitor Center to note posted prediction times for nearby geysers, then build a walking loop through the Upper Geyser Basin. While Fan isn’t predictably posted, the area’s community of geyser watchers and the live webcam from the Old Faithful area can tip you off when activity starts to look promising. Be prepared to wait; bring snacks, water, and a flexible plan.

If Fan isn’t shaping up, don’t waste the window—nearby headliners like Grand, Riverside, Daisy, Castle, and Grotto are all within minutes on the paved path/boardwalk toward Morning Glory Pool. You can often slot an Old Faithful eruption while you keep tabs on chatter about Fan & Mortar.

Geology & History

Like all of Yellowstone’s geysers, Fan is powered by heat from the vast volcanic system beneath your feet. Superheated water rises through constricted underground plumbing; when pressure drops, some flashes to steam, blasting the rest skyward. Fan was documented by early surveys of the basin and remains a favorite precisely because it refuses to run on a schedule.

Best Time to Visit

• Early or late in the day for thinner crowds on the basin trails and softer light.
• Midday can be busy near Old Faithful, but you’ll usually find breathing room along the long boardwalks down-basin.
• Plan for a multi-hour window if you’re determined to see Fan—use nearby predictable geysers to keep the day interesting while you wait.

Wildlife & Etiquette

Bison and other wildlife sometimes drift through the basin. Give them space and time your movements accordingly. Stay on the boardwalks, and never touch thermal water—everything here is scalding and fragile.