16. Black Canyon of the Gunnison National Park, Colorado

Annual visitors: 308,962

Fun fact: The Ute Indian tribe avoids the canyon out of superstition that it’s a cursed place.

If crowds aren’t your thing, skip the Grand Canyon and come here. The steep black cliffs diving into the swift-moving river below are a sight both ominous and awe-inspiring. Advanced hikers and rock climbers are drawn to the canyon, and anyone with the nerve to try the trails will see the leftover rails of the Black Canyon Line, part of the train route that crossed through an area originally thought to be impenetrable. The isolated terrain makes it great nesting territory for birds, and several species of owls and hawks make their homes here.