Enormous lake at the bottom of a unique cave system.

The installation’s official name, “You Who Are Getting Obliterated in the Dancing Swarm of Fireflies,” says it all.

This secluded aqua waterfall in the Grand Canyon is the perfect swimming hole, and the Havasupai tribe's fiercely protected natural wonder.

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

The highest tides in the world come in and out here twice a day, allowing you to essentially walk along the ocean floor.

Despite being one of the most photographed vistas in the Rockies these twin peaks are rightfully known as the "Deadly Bells."

Iran's colorful terraces are a rare geological masterpiece.

A little-visited waterfall in an otherworldly landscape.

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

A toxic ghost town sitting atop a massive coal fire.

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

The ghostly remains of an accidental sea.

These old stone ruins in the Oregon wilderness were once bathrooms and are steeped in legends of murder.

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

A bizarre house filled with an astounding array of collections.

In all of the 29 years it was in operation, no prisoners ever escaped successfully... or so they claim.

An immersive environment that is part haunted house, part choose-your-own-adventure, and part jungle gym.

Dramatic river bend surrounds a natural red-rocked pedestal.

A collision of human error and natural geothermal pressure created this rainbow-colored geologic wonder.

Dodge prohibitionists and slide through the telephone booth in Crif Dogs.

An emerald-green grotto just a short trip from Austin.

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

Rippling sand dunes frozen in the Arizona rock.

One of the only single-person private gravesites in New York City.