Colorado trails · Tonahutu Creek-Flattop Junction Trail
A 8.3-mile out-and-back in Colorado, with 2,799 ft of climbing, topping out at 12,270 ft. Reaches Granite Falls and other pass/summit/waterfall destinations. Managed by Rocky Mountain National Park.
The climbing leans toward the middle third: 51% of the ascent falls between mile 2.8 and mile 5.5. It climbs almost continuously, with little descent to recover on.
On August 31, 2026 — the day this page was generated — first light reaches this trailhead at 6:01 a.m., the sun rises at 6:29 a.m. and sets at 7:36 p.m., and the last usable light fades about 8:04 p.m. (MDT) — 13 h 07 min of daylight. At about 2.7 mph plus 30 minutes per 1,000 feet of climbing, the 16.6-mile round trip takes roughly 8 h 56 min, so leaving the trailhead at sunrise puts you back around 3:25 p.m. — 4 h 11 min before sunset.