Garonne (gärônˈ) [key], river, 402 mi (647 km) long, rising in the central Pyrenees just inside Spain, and flowing generally NE to Toulouse, in SW France, where it swings northwest to join the Dordogne River and forms the Gironde estuary. The Garonne receives nearly all of the smaller rivers of SW France but is navigable only in its lower course; Bordeaux is the head of oceangoing navigation. The river suffers from irregular flow, fluctuating channels, and steep gradients. The famed Bordeaux vineyards overlook the lower river. The Garonne Lateral Canal, 120 mi (193 km) long, parallels the river from Castets to Toulouse.