Sawmill Geyser

Overview

Sawmill Geyser is a classic fountain-type geyser in the Upper Geyser Basin’s Sawmill Complex, a tight cluster that includes Spasmodic, Penta, Churn, and Tardy. It’s only about 10 feet off the boardwalk, so you can watch the action up close without much effort.

What You’ll See

Sawmill erupts in vigorous, rotating bursts that can reach about 35 feet. Eruptions typically last 30–50 minutes, often in a series of separate bursts rather than a single steady column. A hallmark is the “whirring” sound that gives the geyser its name.

How It Behaves

Expect irregular timing. Interconnected plumbing links Sawmill with its neighbors: activity at Spasmodic often precedes Sawmill, while an eruption at Penta can “steal” the water and delay Sawmill until the system reloads. Look for the pool to fill or overflow and for rising bubbles—reliable cues that an eruption could be imminent. Afterward, Sawmill often drains.

Recent Activity

Sawmill was a frequent performer before going quiet in early 2017. It resumed erupting on June 24, 2021. As with all geysers here, behavior can change with little notice, so consider checking recent observations.

Getting There

Start in the Old Faithful area and follow the Upper Geyser Basin boardwalks toward Grand and Castle Geysers; Sawmill sits along that loop in the southern part of the basin.

Photography

Sawmill’s rotating bursts make dynamic images from multiple angles. Low-angle light—especially late in the day—adds color and drama to the steam and spray.

Wildlife and Safety

Bison and elk sometimes move through the basin. Give wildlife plenty of space, stay on the boardwalks, and respect closures—the ground and water are dangerously hot.

Best Time to Visit

• Early morning or late afternoon to dodge the heaviest crowds and for softer light.
• Because eruptions often last 30–50 minutes and can recur roughly every 1–3 hours, you’ve got decent odds if you linger and watch the pool for overflow and bubbling.