Salar de Uyuni (or Salar de Tunupa) is the world's largest salt flat at 10,582 square kilometers (4,086 sq mi). It is located in the Potosí and Oruro departments in southwest Bolivia, near the crest of the Andes, and is elevated 3,656 meters (11,995 ft) above mean sea level. The Salar was formed as a result of transformations between several prehistoric lakes. It is covered by a few meters of salt crust, which has an extraordinary flatness with the average altitude variations within one meter over the entire area of the Salar.

The Greenland ice sheet is a vast body of ice covering 660,235 sq miles, roughly 80% of the surface of Greenland. It is the second largest ice body in the world, after the Antarctic Ice Sheet. Some scientists predict that climate change may be near a "tipping point" where the entire ice sheet will melt in about 2000 years. If the entire 2,850,000 cubic kilometres (683,751 cu mi) of ice were to melt, it would lead to a global sea level rise of 7.2 m (23.6 ft).

Lake Assal is a crater lake in central-western Djibouti. It is located at the western end of Gulf of Tadjoura in the Tadjoura Region, touching Dikhil Region, at the top of the Great Rift Valley, some 120 km (75 mi) west of Djibouti city. Lake Assal is a saline lake which lies 155 m (509 ft) below sea level in the Afar Triangle, making it the lowest point on land in Africa and the third-lowest land depression on Earth after the Dead Sea and Sea of Galilee.

How sure are you of your geographical knowledge? Buzzfeed recently put Americans’ geographical knowledge to the test with a survey in which participants had to write in countries’ names on a blank European political map. Unfortunately, they didn’t fare too well, but some of their responses are hilarious (or hilariously mis-informed). But don’t be so quick to judge Americans – when Buzzfeed posted a similar survey testing Brits’ knowledge of the 50 United States, they also came up short. On the one hand, knowing a country’s states is different from knowing independent countries, but on the other, some U.S. states are larger than some European nations, and some U.S. states have larger economies than some European nations.

“There Were Early Indications that Maxine was Not a Good Fit for the Surgical Team”. (Photo by Studio d'Xavier)

Participants wear traditional clogs as shepherds lead their sheep through the center of Madrid, October 28, 2012. (Photo by Andres Kudacki/Associated Press)

The 3D street painting “Crevasse” by artist Edgar Mueller is seen in this undated picture during the “Festival of culture”, 2008 in Dun Laoghaire, Irland. Edgar Mueller put a part of the eastern Pier into the ice age. This project has been supported by the Goethe Institution Germany. (Photo by Edgar Mueller/Getty Images)

“Keep On Trucking, Mr. Lynx!”. Canadian Lynx Study. (Photo by Josef)