Hallett Peak Trail RMNP is a premier hiking destination in Estes Park, Colorado, covering 10.0 miles with 3200ft of elevation gain. Stats: 10.0 miles, 3200ft gain, Hard. Type: Out-and-Back. Surface: Rock/Dirt. Time: 6-8 hours. Fee: $35 RMNP fee. Dogs: Yes. Permit: No. Wildlife: elk, mule deer, marmots, pikas, golden eagles, Clark's nutcrackers, ptarmigan. Best seasons: July through mid-September; thunderstorm risk above treeline — summit by noon. Hallett Peak at 12,713 feet towers above Dream Lake and offers one of the grandest views in Rocky Mountain National Park — across the Gorge Lakes, Longs Peak, and the Never Summer Mountains. Pack plenty of water — desert and high-altitude trails demand more hydration than you expect. Layers are essential above 10,000 feet. Leave No Trace: stay on designated trails, pack out all waste, and respect wildlife and other visitors.