The Atacama Desert is a plateau in South America, covering a 1,600-kilometer strip of land on the Pacific coast, west of the Andes Mountains. It is commonly known as the driest non-polar place on Earth. Some weather stations in the Atacama have never recorded a single drop of rain in their entire history. The desert's extreme aridity is caused by a combination of factors: the rain shadow effect of the Andes, which blocks moisture from the east, and the cold Humboldt Current from the Pacific, which prevents moisture from the west. Because its landscape is so similar to Mars, NASA often uses the Atacama as a testing ground for Mars rovers. Despite the harshness, it is home to specialized flora and high-altitude lagoons filled with flamingos.