Northwest of Boulder and northeast of Grand Lake, a fabulous hike in the 265,700 acre Rocky Mountain National Park is a 21 mile loop combining the North Inlet Trail with the Tonahuta Creek Trail for a trek along forested creeks by waterfalls and across spiney ridgelines of open tundra.
The trailhead is located near the Kawuneeche Visitor Center on the northeast side of Grand Lake, just off US34. A backcountry campsite permit is required.
Start by hiking north up the Tonahutu Creek Trail past Granite Falls to the Continental Divide Trail. Head southeast on the CDT to the North Inlet Trail. Follow the North Inlet Trail southwest back to the trailhead.
Dont miss the side trail up Flattop Mountain. Keep an eye out for bighorn sheep, elk and mountain lions.
Another cool trail to explore is the Lake Nanita Trail.
Check out Araphahoe Meadows in September for Bull Elk battles.
Overall, North Inlet Trail / Tonahuta Creek Trail is the 5th most popular hiking trail of all 72 hikes in Colorado.