This man-made lake, which regulates the flow of the River Marne, is the largest in Europe. Surrounded by forests and charming villages, this vast expanse of water (4 800ha) is the perfect base for a range of activities, including sailing, water skiing, fishing, swimming and hiking. Nature-lovers will also be in their element thanks to the array of birds, animals, plants and flowers found in this unique environment. The lake is also home to the largest freshwater port in France.