Castle Rock Mountain is a 12,406-foot summit in Montana’s Beartooth Mountains, within the Absaroka-Beartooth Wilderness on the border of Custer and Gallatin national forests. Among the highest peaks in the range, it ranks as the tenth-tallest mountain in Montana. Its nearest higher neighbor is Castle Rock Spire, about 0.65 mile to the east. The mountain’s high alpine setting is defined by ice on both sides, with Sundance Glacier to the north and Castle Rock Glacier to the south.