Madre de Dios (, ) is a department and region in southeastern Peru, bordering Brazil, Bolivia and the Peruvian departments of Puno, Cusco and Ucayali, in the Amazon Basin. Its capital is the city of Puerto Maldonado. It is also the third largest department in Peru, after Ucayali and Loreto. However, it is also the least densely populated department in Peru, as well as its least populous department. It has one of the lowest poverty rates in Peru. The name of the department is derived from the Madre de Dios River, ultimately a tributary of the Amazon, and named by ethnic Spanish colonists. It is a very common Spanish language designation for the Virgin Mary, literally meaning Mother of God. Geography The department is almost entirely low-lying Amazon rainforest. The climate is warm and damp, with average temperatures around [max.: , min.: ]. The rainy season is from December to March, when torrential rainfall causes rivers to swell and often overflow their banks. Annual precipitation can be as much as . The north-western boundary with the Cusco Region is known as the Isthmus of Fitzcarrald, a series of small and low mountains that separate the Madre de Dios River and the Urubamba/Ucayali River basins. Notable rivers in the Madre de Dios River watershed are the Inambari, Tambopata, Manu, Tahuamanu, Las Piedras (also known as Tacuatimanu River), Heath, Acre and Los Amigos. Due to the vast size of the area and its low population density, rivers provide the best way of getting from one town to another. Human activity is invariably confined to riverbanks. A number of explorers have searched for the lost city of Paititi in the jungle within the region. A new road that opened in early 2011 through the area will connect Brazil and Peru for trade, and change the isolation of this area. The only important highway is between the Peruvian cities of Puerto Maldonado and Cusco, away in the Cuzco Department. It is part of the newly built Interoceanic Road between the Pacific and Atlantic Oceans, passing by the border town Iñapari on the Acre river. Flights between Cusco and Puerto Maldonado remain the most common and quicker method of transport between the two. From Puerto Maldonado a road about long leads to the mining town Laberinto ("Labyrinth"). A second road is between the village of Pillcopata and Itahuania (into the Manú National Park). It is