The longest river that flows entirely within France is the Loire.
The Loire runs for about 1,006 kilometres, from its source near Mont Gerbier de Jonc in the Massif Central to the Atlantic Ocean near Saint-Nazaire. Its course passes through or near cities including Orléans, Tours, Angers and Nantes. More than a fifth of France drains into its basin.
The Loire is sometimes confused with the Rhône because the Rhône carries more water, but the Rhône rises in Switzerland and therefore does not flow entirely within France. The Garonne also begins in Spain, while the Seine is much shorter. The Loire’s relatively modest average discharge, compared with rivers such as the Rhône, reflects its strongly seasonal flow.
Historically, the river was an important transport route, although shallow water and shifting channels limited navigation. Its middle and lower valley is famous for castles and vineyards; the Loire Valley between Sully-sur-Loire and Chalonnes has been a UNESCO World Heritage Site since 2000.