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

Ethiopia's "smoking mountain" is in one of the hottest regions on the planet and is home to two lava lakes.

Two waterfalls flow down the cliff faces decorated with rare natural basalt columns.

Village situated on a narrow volcanic escarpment.

A natural arch offers panoramic views of Yangshuo's karst hills.

The unique waterfall in Iceland's south features a backdrop of geometric black lava columns.

An abandoned whaling station on an active volcano offers hot springs in Antarctica, surrounded by ruined giants of industry.

The 3.8 billion-year-old rock proves that tectonic plates may have been shifting longer than we thought.

Think you have a tough job? Try carrying 200 kilos through a cloud of sulfur down the side of a volcano.

Mount Nyiragongo has erupted at least 34 times since 1882 and is home to the world's largest lava lake.

A city continually buried under the ash of a volcano that has been erupting for more than 15 years.

Take a drunken tour inside the world's largest known geode.

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

Unique geological formations in China, featuring some suggestive shapes.

Oregon's unexpected high desert, displaying layers of time in a colorful show.

The cell which saved the life of Ludger Sylbaris, "the man who lived through Doomsday."

Climb right into the heart of this colorful Iceland volcano.

Eons old volcanic activity created one of the most stunning rock formations in the United States.

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

According to the locals, the sands of this secluded Norway beach are infused with gemstone particles.

Plains of ash and pair of semi-active volcanoes contribute to the otherworldly beauty of this little-known Vanuatu island.

This naturally heated mountainous creek has created a group of neon blue pools of potentially deadly boiling water.

Nature’s skyscraper launches out of the terrain with attitude.

A star fort along the C&O Canal in western Maryland that protected America in three wars.