Flattop Mountain Trail RMNP is a premier hiking destination in Estes Park, Colorado, covering 8.5 miles with 2800ft of elevation gain. Stats: 8.5 miles, 2800ft gain, Hard. Type: Out-and-Back. Surface: Rock/Dirt. Time: 5-7 hours. Fee: $35 RMNP fee. Dogs: Yes. Permit: No. Wildlife: elk, mule deer, marmots, pikas, ptarmigan, golden eagles. Best seasons: July through September; flat summit plateau requires navigation skills in weather. Flattop Mountain's broad summit plateau at 12,324 feet offers access to the Continental Divide Trail and sweeping views of the Kawuneeche Valley and Never Summer Range — a gateway to RMNP's remote west side. 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.