Seine Commercial craft (barges and push-tows) can use the river from Marcilly-sur-Seine, to its mouth. At Paris, there are 37 bridges. The river is only above sea level from its mouth, making it slow flowing and thus easily navigable. The Seine Maritime, from the English Channel at Le Havre to Rouen, is the only portion of the Seine used by ocean-going craft. The tidal section of the Seine Maritime is followed by a canalized section ("Basse Seine") with four large multiple locks until the mouth of the Oise at Conflans-Sainte-Honorine (170 km). Smaller locks at Bougival and at Suresnes lift the
Seine policemen from the Pont Saint-Michel and other locations in Paris. Dredging in the 1960s mostly eliminated tidal bores on the lower river, known in French as ""le mascaret."" In 1991 UNESCO added the banks of the Seine in Paris—the "Rive Gauche" and "Rive Droite"—to its list of World Heritage Sites in Europe. Since 2002 Paris-Plages has been held every summer on the Paris banks of the Seine: a transformation of the paved banks into a beach with sand and facilities for sunbathing and entertainment. The river is a popular site for disposal of bodies of murder victims. In 2007, 55