Medicinal spa created with the discharge from a geothermal energy plant.

An Italian crevasse filled with abandoned buildings gives visitors a look at the world without humans.

This secluded aqua waterfall in the Grand Canyon is the perfect swimming hole, and the Havasupai tribe's fiercely protected natural wonder.

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

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

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

The vast, legendary catacombs hold secrets much stranger than stacked bones.

This breathtakingly beautiful botanical garden is home to a mob of wonderful wallabies.

Local lore says two enemy dragons live within these breathtaking mountain lakes.

An annual celebration of the region's successful elk reintroduction program.