Black Canyon of the Gunnison National Park

At this impossibly sheer, narrow canyon in southwestern Colorado—at its thinnest points, the gorge spans just 40 feet at the Gunnison River and 1,100 feet at the rim—rock walls plunge as deep as 2,722 feet.

Intrepid hikers and rock climbers can venture into the depths on several very steep, unmaintained trails. Other visitors prefer to peer into the chasm from a network of trails lining the north and south rims. Anglers love this place for its gold-medal water for trout fishing.