Day hikers can walk along the rim of a canyon so deep that its bottom almost never sees sunlight, via the Warner Point Nature Trail in Colorado’s Black Canyon of the Gunnison National Park.
To reach the trailhead, take Colo. Hwy. 347 into the park then turn left onto South Rim Road, following it all the way to High Point. Several scenic vistas along the way are worth stopping at; the most dramatic by far overlooks the Painted Wall. The 1.5-mile round trip trail begins due west of the High Point parking lot.
The park follows 12 miles of the Black Canyon, a scenic gorge that drops as much as 2,250 feet from rim top to river below. The Warner Point Nature Trail sits just past where the road runs out:
Map of the Warner Point Nature Trail:
Peregrine falcons – the world’s fastest flyer with 200 mph dives – resides in the canyon (photo courtesy of NPS/Lisa Lynch):
The Painted Wall, Colorado’s tallest sheer cliff at nearly half a mile high, sits northeast of Warner Point (photo courtesy of NPS/Lisa Lynch):
The Painted Wall is almost as tall as the world’s highest building, Dubai’s Burj Khalifa, which is 2717 feet.; the Empire State Building is No. 4 and the Willis Tower – formerly the Sears Tower – is No. 5 (illustration courtesy of NPS):
Here's a full description of the trail.
Learn more about national park day hiking trails in my Best Sights to See at America’s National Parks guidebook.