The Loire is the longest river in France with a length of 629 miles (1,012 km), rising in the the Massif Central and flowing north through the Loire Valley and then west to the Atlantic Ocean. Rising in the Cévennes range of the southeastern quarter of the Massif Central near Mont Gerbier de Jonc, it flows northward for over 620 miles (1,000km) through Nevers to Orléans, then west through Tours and Nantes until it reaches the Bay of Biscay at St Nazaire. Its main tributaries include the Nièvre, Maine and the Erdre rivers on its right bank, and the Allier, Cher, Indre, Vienne, and the Sèvre Nantaise rivers to the left bank.
The Upper Loire runs from the source to the confluence with the Allier near Pouilly-sur-Loire south of Orleans. In the upper basin the river flows through a narrow, incised valley, marked by gorges and forests on the edges and is lowly populated.
The Loire Valley in the Middle Loire is a 190 mile (300km) stretch in the western reach of the river starting downsream of Nevers, through Orléans and Tours, finishing at Nantes 35 miles (56km) from the Atlantic Ocean. The Loire Valley is a UNESCO World Heritage Site due to its fine assortment of castles and a famous wine growing region home to Sancerre, Pouilly Fume, Touraine and Anjou wines.
The Loire flows into the Atlantic Ocean between Saint-Nazaire and Saint-Brevin-les-Pins, connected by a bridge over the river near its mouth. The tidal stretch of the river extends 37 miles (60 km) past Nantes with a width of nearly 2 miles (3km), It has oil refineries, the port of St-Nazaire and 40,000 hectares (99,000 acres) of wetland and fens, which form unique habitats for migratory birds as well as the beaches of Le Croisic and La Baule along the coast line.