The name Seine comes from the Latin Sequana, which in turn comes from the old Celtic word squan, meaning serpentine, the Seine follows a very tortuous 776 kilometre route from its source on the Langres plateau to the ocean, 365 kilometres of this is below Paris. This well tamed watercourse crosses the city roughly from east to west along a curved path. The average flow of the river is between one and ten cubic metres per second, and the depth averages six to eight metres.
The river is navigable for freight all the way to the Atlantic ocean and for a considerable distance above Paris, and barges are a common sight on the river at Paris. Two thousand years ago, this river was famous for the purity of its water and the abundance of fish that it contained, it is still quite clean. people ask if the Seine provides drinking water to the city. In fact, roughly half of Paris' drinking water is obtained from natural springs east of the city, and is clean enough that no treatment is required beyond a squirt of chlorine to keep it pure during the trip to the city. The remaining half is obtained from the Seine and Marne rivers quite a distance upriver, after purification. the Seine is artificially maintained at a level higher than its natural level, by dams and locks downstream. The river only drops about 30 metres on its 200 kilometres journey to the Atlantic, and in the days when it flowed at its natural level, most of the riverbed was sand, with only a narrow stream of water flowing down the middle.
One of my favourite things to do in my trip, it was to walk along the banks of the river Seine. This river winds its way through the heart of Paris, decorated on both sides by some of the most famous and beautiful buildings of the capital. On a sunny day it is so relaxing and wonderful to stroll along the banks of the river. On several places you'll come across little stalls selling books, posters, and of course the usual tourist things.