The Thunder Knob Trail switchbacks gently to a knob above Diablo Lake with views of surrounding peaks. 

• Difficulty: Moderately easy. 
• Distance and elevation: 3.6 miles (5.8 km) roundtrip with 425 ft (130m) elevation gain.
• Access: Drive State Route 20 to milepost 130, Colonial Creek Campground (24 miles east of Marblemount and 63 miles west of Winthrop). Park at the signed trailhead on the north side of the highway at the entrance to the campground.
• Leashed dogs allowed.
• The trail and parking area can be very crowded during summer months.

Detailed trail description.