Ecosystems

This series of Scottish caves has no clear purpose other than baffling historians.

A wellspring of creativity in an already artsy East London neighborhood.

This limestone cave offers an incredible view of the Río Grande de Arecibo valley.

The Twisted Trees of Alticane are an unnerving grove of Quaking Aspen, apparently mutated from a single source, giving them a twisted and unnatural appearance.

Deep scars on the earth left by the Ice Age.

Deadly scalding and one of the largest hot springs in the world.

Ancient rock-hewn town that witnessed key events of Georgian history.

In a long-dry lake bed, these groups of massive stone pillars bear a striking resemblance to clumps of everyone's favorite fungi.

The second-deepest known cave on Earth, hidden in an extremely remote mountain region.

A lake formed in the basin of a massive impact crater takes the shape of an unbroken ring when viewed from above.

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

An arresting arch punched straight through a mountain provides one of the most scenic spots, and challenging climbs, on the planet.

This parking garage has given itself over to graffiti artists and the neighborhood can't thank them enough.

Unexplained bald patches in the landscape grow and recede over time, as though they are somehow alive.

The "World's Largest Underground Business Complex," a 55,000,000-square-foot city underneath Missouri.

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

From the sky, a kaleidoscope of color brightens the grey landscape of the San Francisco Bay.

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