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
Layout of the Port of Tianjin port area is expanding fast, and it is expected to reach a capacity of 100 Mt per year by 2015. Further up the Haihe estuary is the Donggu Fishing Port, which still moors 400 (mostly small) fishing boats. The Tianjin Xingang Fairway is divided into the Main Shipping Channel, the Chuanzhadong Channel, and the Northern Branch Channel. The Dagusha Channel and the Haihe river channel are separate fairways with slightly different regulations. The Dagusha Channel (大沽沙航道) is wholly separate from the Main Channel. It is 27.5 km long from safe water (12 m isobath) to the mouth of the Haihe.