Incredible places: A window onto extraordinary landscapes on Earth

The Eye of the Sahara, also known as the Richat structure, stands out like an oversized ammonite among the sand dunes of the Sahara desert in Mauritania.

China's southwestern karst landscape is pockmarked with dozens of enormous sinkholes that look like they were made with a cookie cutter — and scientists keep finding new ones.

Snake Island was isolated from the Brazilian mainland at the end of the last ice age, trapping Earth's only known population of highly venomous golden lancehead pit vipers on a rock in the Atlantic.

Turkey's magical "fairy chimneys" in Cappadocia were carved out of an ancient volcanic landscape over millions of years before humans turned them into hiding dens.

The Cave of Crystals in Chihuahua, Mexico, is buried almost 1,000 feet (300 meters) beneath Earth's surface and contains giant gypsum crystal beams that are up to 37 feet (11 m) long.