The Gironde is a navigable estuary in southwest France and is formed from the meeting of the rivers Dordogne and Garonne just downstream of the centre of Bordeaux. Covering around 635 km², it is the largest estuary in western Europe. The Gironde is approximately 80 km long and 3–11 km wide and the French département Gironde is named after it. The Gironde is subject to very strong tidal currents and great care is needed when navigating the estuary by any size or type of boat.