The tallest stationary dunes on Earth also happen to sing.

The largest ice cave in the world is thought to be the entrance to hell according to Austrian legend.

This peculiar lake of pitch is so thick and viscous that one can walk on its surface.

A centuries-old iron mine is now a paradise for explorers, divers, and spelunkers.

A stunning silver lining to global warming's gloomy cloud.

In Northeastern Iceland lies something of an oxymoron: a steaming desert.

Mother Nature outdoes herself with this stunningly beautiful set of caves carved into marble.

Not one, not two, but three natural bridges remain in this captivating spot post-sinkhole.

A lush desert oasis in the shape of a narrow crescent.

Hundreds of glow-in-the-dark objects light up a museum in a historic zinc mine.

One of the most extreme deserts in the world, these snow-free valleys harbor life, despite the hostile environment.

A mysterious ancient network of thousands of perfectly straight lines stretching across miles of Bolivian desert.

Sunset-colored dunes of volcanic ash make taking a poor photo impossible.

Once thought to be the oldest living tree in the world, Methuselah was germinated before the Egyptian pyramids were built.

This 4,000-foot-diameter hole is touted as "the most well known, best preserved meteorite crater on Earth."

Eons ago, a rushing lava river formed this pristine passage through solid rock.

Devilish landscape, once cinema home to giant alien bugs, now derelict roadside attraction.

Rippling sand dunes frozen in the Arizona rock.

Two creeks flow out of either end of this canyon in opposite directions.

Sandstone rock formations that look like they belong on the cover of a progressive rock album.

Order cookies baked by cloistered nuns in a 400-year-old monastery.

This massive solar generating facility in the Nevada desert has been plagued by difficulties.

This Irish show cave is said to have been the site of a Viking massacre that claimed 1,000 lives.

Site of the largest impact event to occur over land in Earth's recorded history.