It encompasses an area of 678 square miles (1,756 km2) spanning parts of Custer, Boise, Blaine, and Elmore counties, and is bordered to the east by the Sawtooth Valley.

[10][11] Evidence of past glaciation given remnants of the glaciers such as glacial lakes, moraines, horns, hanging valleys, cirques, and arêtes.

[10] In 2010, scientists from Idaho State University discovered the Sawtooth Fault near the base of the mountains, running for 40 mi (64 km), near Stanley and Redfish Lake.

The Sawtooth Fault’s latest period of significant seismic activity occurred between roughly 4,000 and 7,000 years ago.

[3] There are 40 trails totaling nearly 350 miles (560 km) in the Sawtooth Wilderness that can be used for day hiking, backpacking, and horseback riding and accessed from 23 trailheads.