Atacama is the driest desert on Earth and recent scientific studies demonstrated that the soil in the region is about 25-30 million years old. The Atacama landscape is characterized by highlands, volcanoes, salt lakes, lagoons, hot springs, strange rock formations and sand dunes. Famous natural landmarks include Licancabur Volcano, Valle de la Luna, Parque nacional del Valle de la Muerte, El Tatio Geysers and the Atacama Salt Flat. The Altiplano, meaning “high plain” in Spanish, is a high plateau in the Andes Mountains stretching across the borders of Chile, Bolivia, Argentina and Peru. Altiplano is a place of superlatives: It holds the world's highest navigable lake, Titicaca, and the largest salt flat, Salar de Uyuni. It is the second largest mountain plateau in the world, after that of Tibet. It also is home to many active volcanoes.