The Patagonian Desert, also known as the Patagonian Steppe, is the largest desert in Argentina and the eighth-largest in the world. It is a cold winter desert, located primarily in the rain shadow of the Andes Mountains to the west. Because the prevailing winds from the Pacific lose their moisture as they climb the Andes, the land to the east remains extremely dry. The landscape is characterized by vast, treeless plains and plateaus with rocky soil. Temperatures rarely exceed 12°C on average and frost is common year-round. Despite its name, it is home to varied wildlife, including the guanaco (a relative of the llama), the rhea (a flightless bird), and the Patagonian mara. Charles Darwin famously explored this region during his voyage on the HMS Beagle, noting its unique geology and the fossilized remains of giant extinct mammals.