Boulder Mountain in Utah, USA makes up half of the Aquarius Plateau of South Central Utah in Wayne and Garfield counties. The mountain rises to the west of Capitol Reef National Park and consists of steep slopes and cliffs with over 50,000 acres (200 km²) of rolling forest and meadowlands on the top. It is the highest timbered plateau in North America and is part of the Dixie National Forest.
Utah Scenic Byway 12 traverses the eastern side of the mountain from Torrey through Boulder and on to Escalante. A series of unpaved backcountry roads and jeep trails provide access to the top during the brief snow free time, which is usually only a few months from July to September.
The Boulder Mountain cinquefoil (Potentilla angelliae) is a rare species of plant that is endemic to Boulder Mountain.