148 feet long and in the middle of a verdant forest.

A memorial to the tens of thousands of Irish who fled to North America during the Great Famine.

A little known Colombian theme park of giant curiosities.

A remarkable geological formation resembling a forest made of stone.

This scalding hot river was thought to be a myth until one geoscientist made it his quest to study the mystical waters.

A completely underwater art museum sends a stark message about humans' impact on the environment.

Over two-thirds of the world's population of giant tortoises live among this coral formation.

A tiny plaque hidden miles into the Washington wilderness is all that remains to honor a shipwreck that left 18 people dead.

The lush coastal city of Astoria is riddled with forgotten secret sidewalks.

Remember that scene in the Matrix, when Neo is in the big white room with all the weapons flying by? Well, this is what it would look like if he had wanted trees instead of guns.

These towering spires and glowing walls are carefully crafted from hundreds of thousands of icicles.

Keshwa chaca, among the last handwoven Incan bridges, crosses Apurimac Canyon in Peru.

This everlasting lightning storm may be the world's largest generator of ozone.

Astronomical observatory above Lake Titicaca.

A remote candy-striped mountain in the Peruvian Andes straight out of the pages of Dr. Seuss.

A town church once nearly submerged by the damming of a river is now hauntingly visible as the water recedes.

An underwater road considered a possible Atlantis location.

These spectacular ruins were built by Spanish padres in the 17th century.

Named for the DeFoe novel inspired by a stranded sailor, this island is known for its rare plants and extreme beauty.

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

This stunning mass of ice spans 121 square miles and is still growing.

The Buddhist temples of Yamadera, built into a mountain side, feature a viewing deck with sweeping views.

This old cement mine has been used as everything from a mushroom farm to a recording studio.

This whimsical castle of grottoes was the labor of love of a French postman, and one of the greatest achievements of outsider architecture.