The geography of the country exhibits a great variety of terrain and climates. Bolivia has a high level of biodiversity, considered one of the greatest in the world, as well as several ecoregions with ecological sub-units such as the Altiplano, tropical rainforests (including Amazon rainforest), dry valleys, and the Chiquitania, which is a tropical savanna. These areas feature enormous variations in altitude, from an elevation of above sea level in Nevado Sajama to nearly along the Paraguay River. Although a country of great geographic diversity, Bolivia has remained a landlocked country since the War of the Pacific. Puerto Suárez, San Matías and Puerto Quijarro are located in the Bolivian Pantanal.