The world's highest and most dangerous infinity pool lies at the precipice of Victoria Falls.

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

Two geological phenomena in one precarious locale: a towering stone window, and a deep blue void.

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

Breathtakingly blue walls shimmer inside the "Glacier Behind the Town."

An Australian lake whose pink hue defies scientific explanation.

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

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

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

A faux desert landscape in the middle of the jungle that sprouts oases during the rainy season.

Little island known for its massive beachfront "flowerpot" pillars.

An isolated dive site teeming with cnidarians.

A massive underwater sinkhole made famous by Jacques Cousteau.

Moss and stone turn this waterfall into an otherworldly liquid veil.

Tubing through a cave lit with glowworms is a magical underground experience.