A subterranean playground in an abandoned slate mine.

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

This astonishingly geometric cave has inspired everyone from Jules Verne to Pink Floyd.

A charmingly eccentric magma chaser presents his complete history of the island's eruptions since 1947, in cinematic form, just for you.

One of the world's few mounted blue whales, its jaws are hinged open allowing visitors to descend into a lounge.

Ancient cliffs resembling a kilt on Scotland's second largest island emit an entrancing sound.

Mysterious rocks that ring musically when struck.

An Australian lake whose pink hue defies scientific explanation.

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

A battle between nature and architecture in the Cambodian jungle.

Bring your own cardboard to the slippery slopes of concrete hidden in a neighborhood park.

Hot springs monkey spa in the middle of Hell's Valley.

An artsy hidden staircase leads to breathtaking views of San Francisco.

Stunning wetlands ablaze with pink lotus flowers.

A seemingly endless landscape of pure salt stretches far across Bolivia.

One man has installed bathtubs into the Utah desert floor to harness the powers of a natural hot spring.

This geothermal hot spring hides beneath a slowly growing mineral dome.

Medicinal spa created with the discharge from a geothermal energy plant.

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

A massive underwater sinkhole made famous by Jacques Cousteau.

An exquisite tunnel of cascading flowers.

The world's highest and most dangerous infinity pool lies at the precipice of Victoria Falls.

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

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