Though only the second-longest river in France (behind the Loire), the Seine is of key importance, as it flows through Paris. Starting on the Plateau de Langres near Dijon, the Seine weaves northwest for 485 miles to enter the English Channel near Le Havre. Along the way, it passes through Troyes, Fontainebleau, and Rouen. The Seine is France's chief transport waterway, along with its tributaries the Marne and Oise.