Between Rouen and the sea, ocean-going vessels of up to in length, and 150,000 tons in weight can travel the Seine. This section of the river has a length of about . Ships of a draft of up to can circulate. Draft is a word describe the height of the part of a ship that is below the water line. There are three bridges in this section. They can be raised. The maximum air draft (or height above the water line) of a ship is . Because there are few briges, the river can be crossed by ferry, at different locations. The port of Rouen is an important maritime port in France; it is the most important port in Europe for cereals, and the most important port in France for flour and fertilizers. Even if the port of Le Havre is more important for petroleum, that of Rouen is still important. About 25 million tons of produce is handled by the port of Rouen each year.