Alien rock formations grown from the sands of an Australian national park.

The labyrinthine storm tunnels beneath the city of Melbourne are ruled by a band of urban explorers.

A clear example of the process of erosion in action.

An opal mining town in the middle of Australia where people live, worship, and shop underground.

The only pollutant in the clear blue water is sunscreen.

A castle hand-built by a Spanish dreamer in the Australian tropical jungle.

This gracefully curving formation looks like a massive wave that was suddenly turned to stone.

Occult books, tarot, oddities.

An abandoned railroad tunnel is now filled with bioluminescent bugs.

Australian Lake set aglow by Noctiluca Scintillans.

A stunning, two-tiered waterfall made famous by poets, artists and the legend of a ghost dog.

The first declared National Monument in the United States.

Towering basalt columns, a creation of fire and ice.

The feral felines of Roosevelt Island have a small army of allies and an abandoned hospital all to themselves.

An Australian lake whose pink hue defies scientific explanation.

An ancient capital city that dates back 3,000 years old and harbors many surprises.

A lovers' beach, tucked below the surface of the island, provides a safe haven for romance.

The oldest family-run luncheonette in New York, last renovated in 1948, still serves food and drinks the old-fashioned way.

A beautiful, dense forest in the shadow of Mount Fuji, with a tragic reputation.

A church of bones, decorated with 40,000 human skeletons.

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

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

These fantastically named natural pools look like something out of a Scottish myth.

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