Sawmill Geyser, named for the whirring sound it makes during its eruption, is a geyser in Yellowstone National Park, Wyoming, United States.

The geyser was named by Antoine Schoenborn of the Hayden Geological Survey of 1871.

Sawmill is the largest geyser in the Sawmill Complex, a region of geothermal features located in Upper Geyser Basin approximately 10 feet off the path.

Another eruption indicator is when Sawmill fills with the rest of the geyser's water in the Sawmill Complex or starts to overflow, bubbles tend to rise to the surface.

[3][2] According to reports submitted to GeyserTimes.org, Sawmill's last observed eruption for over four years occurred during the morning hours of January 29, 2017.