Roaring Mountain is a mountainside of steaming fumaroles (steam vents) located east of the Twin Lakes and north of the Norris Geyser Basin on the Grand Loop Road.

Visitors during the late 1800s and early 1900s said that this mountainside used to roar very loudly. In the early 1900s, the number, size, and power of the fumaroles were much greater, and produced a racket that could be heard for miles. This large, acidic hydrothermal area (solfatara) is covered by fumaroles that may hiss, roar, sigh, or whistle. The run-off from Roaring Mountain makes North Twin Lake much more acidic than its neighboring South Twin Lake.

The fumaroles are most easily seen in the cooler, low-light conditions of morning and evening. There are pull-offs on either side of the road for visitors to safely pull over and view Roaring Mountain.

Information provided from the National Park Service.