The geography of Bolivia is unique among the nations of South America. Bolivia is one of two landlocked countries on the continent, and Bolivia is more rural than urban. The main features of Bolivia's geography include the Altiplano, a highland plateau of the Andes and Lake Titicaca (Lago Titicaca), the largest lake in South America and the highest commercially navigable lake on Earth (which it shares with Peru).
The most prominent feature of the Altiplano is the large lake at its northern end, Lake Titicaca. At 3,811 m (12,503 ft) above sea level, it is the highest commercially navigable body of water in the world. With a surface area of 9,064 km2 (3,500 sq mi), it is larger than Puerto Rico and is South America's second largest lake by surface area. Lake Titicaca is also deep, about 370 m (1,214 ft) at its deepest, but with an average depth of 215 m (705 ft); its volume of water is large enough to maintain a constant temperature of 10 °C (50 °F). The lake actually moderates the climate for a considerable distance around it, making crops of maize and wheat possible in sheltered areas.
Lake Titicaca drains southward through the slow-moving, reed-filled Desaguadero River to Lake Poopó. In contrast to the freshwater Lake Titicaca, Lake Poopó is salty yet shallow, with depths seldom more than four metres.