Seemingly grown on some other world, these New Mexico rock formations look like a disused science fiction set.

A beautiful geyser under environmental threat.

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.

The ancient dwellings of the Puebloans, located in the cliffs of majestic mesas.

The land is full of geologic eye candy, such as otherworldly spires, mushroom-shaped hoodoos, and prehistoric fossils.

Explore the largest pure gypsum deposit in the world, and go dune sledding while you're at it.

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

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.

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

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

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

Dramatic river bend surrounds a natural red-rocked pedestal.

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

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

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

On the Oregon coast there is a natural hole that seems to be draining the sea.

America's most famous museum of medical oddities is home to the remains of Albert Einstein's brain.

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

Rippling sand dunes frozen in the Arizona rock.

The artist James Turrell is repurposing an extinct volcano crater as an observatory to experience the cosmos.

An artificial crater field that trained astronauts for lunar exploration.