Argentina is divided into twenty-three provinces and one Autonomous City. Buenos Aires Province is divided into 134 partidos, while the remaining Provinces are divided into 376 departments. Departments and Partidos are further subdivided into municipalities or districts. With the exception of Buenos Aires Province, the nation's provinces have chosen in recent years to enter into treaties with other provinces, forming four federated regions aimed at fostering economic integration and development: Center Region, Patagonic Region, New Cuyo Region, and the Argentine Greater North Region.The total surface area is 2,766,891.2 km2, of which 30,200 km2 is water. Argentina is about 3,900 km long from north to south, and 1,400 km from east to west. The highest point above sea level is in Mendoza province at Cerro Aconcagua. The lowest point is Laguna del Carbón in Santa Cruz province, −105 m below sea level. The major rivers are the Paraná, the Pilcomayo, Paraguay, Bermejo, Colorado, Río Negro, Salado and the Uruguay. There are several large lakes including Argentino and Viedma in Santa Cruz, Nahuel Huapi between Río Negro and Neuquén, Fagnano in Tierra del Fuego, and Colhué Huapi and Musters in Chubut. Lake Buenos Aires and O'Higgins/San Martín Lake are shared with Chile. Mar Chiquita, Córdoba, is the largest salt water lake in the country. There are numerous reservoirs created by dams. The 4,665 km long Atlantic coast has been a popular local vacation area for over a century, and varies between areas of sand dunes and cliffs. The continental platform is unusually wide; this shallow area of the Atlantic is called the Argentine Sea. The waters are rich in fisheries and possibly hold important hydrocarbon energy resources. The two major ocean currents affecting the coast are the warm Brazil Current and the cold Falkland Current. Because of the unevenness of the coastal landmass, the two currents alternate in their influence on climate and do not allow temperatures to fall evenly with higher latitude. The southern coast of Tierra del Fuego forms the north shore of the Drake Passage.