A roaring, awe-inspiring double cascade of icy water flows through woodland Oregon like something out of a Tolkien novel.

Under the right circumstances, this waterfall in Yosemite briefly turns a luminescent fiery orange.

One man has carved a number of natural New Mexico caves into psychedelic sandstone temples.

For two weeks every June, fireflies in the Smoky Mountains perform an astonishing light show.

Crystal clear lake with a shoreline of travertine located in a Colorado canyon.

Remants of foundations, streets, and streetcar tracks inhabit the cliffs where a landslide occurred in 1929.

These remote Florida islands have a history of sea turtles and sunken treasures, and one of the world's largest coastal brick fortresses.

Wondrous sandstone hoodoos where Native Americans collected clay for pottery, 9,000 years ago.

Most-visited and most-photographed slot canyon in the American Southwest.

The fifth-longest natural arch in the world, and the longest outside China.

This raised bulls-eye visible from space was the subject of an intense geologic controversy.

The hike through a narrow river flanked by the 2,000-foot-tall walls of Zion Canyon is one of the best in the world.

Ancestral Puebloan ruins, natural arches, and box canyons abound in this seldom-visited corner of Monument Valley Navajo Tribal Park.

An arsenic-filled pool in the Grand Canyon takes on the appearance of a giant, overflowing pumpkin.

Wee (and not so wee) footprints that insects and reptiles of the Paleozoic Era left behind.

An abandoned mine where dreams of quicksilver trickled away over 75 years ago.

An abandoned quicksilver mining town surrounded by the Big Bend parks.

Giant pinnacles in the sun-scorched lands of Southern Utah have been nicknamed "white ghosts."

Dramatic river bend surrounds a natural red-rocked pedestal.

Rippling sand dunes frozen in the Arizona rock.

Once a thriving business district, this former shopping area is now an urban ghost town in the heart of the city.

This abandoned iron furnace was one of the first to use coke—a type of high-carbon fuel—to make iron.

Stroll through a wonderland of stupendous moss-covered trees.

The wreckage of a deadly bomber plane crash can still be found near an Arizona peak.