A glowing underwater cliff attracts marine life and divers in equal measure.

Once an ambitious nature spa, these forest ruins now provide a serene monument to failure.

Erosion and time have created a naturally-formed water park.

A flooded Mexican cave that hides a river beneath the water.

A limestone wonderland of water and subterranean secrets.

Enchanting cave with a river crashing through the roof.

A unique seaside cave where Aleister Crowley faked his own death.

An emerald-green grotto just a short trip from Austin.

A humid oasis combines recreation with exploration in a unique underwater cavern.

Curious cave that stays a cool 56 degrees all year long.

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

Once thought to be the mysterious work of a witchy prophetess, a well with unusual properties turns objects into "stone".

A metal tree emits eerie, melodic notes on top of Lancashire's Crown Point.

This former Masonic hall has been turned into an art project that uses even more metaphysical iconography.

An oil baron's wild paradise and the winner of an ill-fated air race.

Nature's biggest mammal swims in landlocked Oklahoma.

Buildings that dynamite couldn't bring down were abandoned because of bathroom issues.

An abandoned vacation home spent a decade taking on legends. It's now taking on water.

Where Aleister Crowley taught magick in "La Chambre Des Cauchemars," his "Chamber of Nightmares."

The northernmost point in Denmark is a turbulent sandbar created by two clashing seas.

A Victorian mansion, painstakingly reproduced to appear just as the the Munster's family home did on TV.

A modernist landscape of water and sci-fi concrete.

This incredible Chinese theme park may be the largest bootleg in history.

Copenhagen's celebrated theme park and gardens.