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 River (Manitoba) Floodway into what is known as the "Seine River Siphon", which allows a flow of up to ; any additional flow is diverted onto the Floodway. During a wet spring, the river often overflows its banks, sometimes flooding nearby houses. During a dry summer, the river is often reduced to a trickle. Within the city, the Seine travels a tortuously meandering course, reaching the Red River at St. Boniface just north of The Forks. The lower section of its course in the city marks the east-west boundary between the southern section of St. Boniface and the suburb of St. Vital.