"The Seine is dredged and oceangoing vessels can dock at Rouen, 120 km (75 miles) from the sea. Commercial riverboats can use the river from Bar-sur-Seine, 560 km (350 miles) to its mouth. At Paris, there are 37 bridges.The river is only 24 metres (80 feet) above sea level, 446 km (277 miles) from its mouth, making it slow flowing ..." (Quoted from site)