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
Almada River of Castelo Novo, Sambaituba and Aritaguá. From Aritaguá the river flows south parallel to the sea shore past Iguape, and empties into the Atlantic Ocean near the town of Ilhéus. The Almada River supplies water to the towns of Itajuípe and Coaraci. It supplies about 70% of the water used by residents of Itabuna. In the summer of 2015–16 water rationing was imposed due to low levels in the river, which had dried up in some sections. As of 2010 half the domestic sewage from Aritaguá was released directly into the river, while 25% went into pits in backyards, and