My suggestion
Have some kind of a bridge above the water in cities like Paris so ships (Corvettes, Destroyers and Transport Ships) could pass in the rivers from cities to make shorter arrival times and add more actions into the game by the danger of your capital being attacked from the water.
Have some kind of a bridge above the water in cities like Paris so ships (Corvettes, Destroyers and Transport Ships) could pass in the rivers from cities to make shorter arrival times and add more actions into the game by the danger of your capital being attacked from the water.