Length: 7 miles (round-trip from Rat Lake) or 8 miles (round-trip via Garnet Mountain Trail)
Duration: 3.5 hours
Elevation: 1,850 feet
Activities: Hiking, mountain biking, camping, cross-country skiing
Crowds: Moderate traffic
This hike has two routes. One follows an old double-track logging road, climbing steadily until the very end. The other is a steep singletrack that ties into the logging road about a half-mile below the peak. The singletrack trail is roughly 4 miles to the top, gaining 2,800 feet of elevation along the way. The double-track trail winds around the back side of the mountain, passing Rat Lake, a few ponds, and the turnoff to Pioneer Lakes along its 4-mile length. Both routes offer great views—the canyon's forested slopes and distant peaks make for epic scenery. Near the summit, the trail passes through a livestock fence and climbs to a fire lookout tower atop the mountain. The tower was built in 1930 and is available to rent for camping through the Montana Recreation Rental Program. Carry bear spray.
Garnet Mountain holds onto snow through the spring. The snow can be deep at times, but the trail is still passable. The trail's best conditions range from June through October. During the winter, cross-country ski until the incline becomes too much, then hike to stay at the lookout, which can be rented year-round.
From Bozeman, take Hwy. 191 south toward Gallatin Canyon. When you get into the first section of tighter turns, watch for signs for Storm Castle Rd and the old concrete CCC bridge on the left. Cross the bridge, turn right, and continue about 2 miles. For the singletrack route, look for a small parking area on the left; this lot also serves the Storm Castle trailhead. The marker for Garnet Mountain is across the road. For the double-track option, continue on the Storm Castle Rd., taking a right at the fork. Park at the end of the road.
Map courtesy of Robert Stone's Day Hikes Around Bozeman, Montana.