The Seine river runs through Paris and into the English channel. The boat would be in France.
The River Seine is in France.
If you were sailing and ran into a river cataract you would have to get out and go around
The most commonly known river in France would be the Seine.
The River Seine passes through several French cities. The most famous city incorporating the Banks of the Seine is Paris, France. Others include Le Havre, Rouen, Honfleur, Tancarville.
I believe you pronounce it sine just like you would in "Sign"
Southerly mostly
That would be Paris, Texas. Paris, France has the River Seine.
Loire River
It would be hard to chose between the Loire, the Seine, and the Rhone.
The channel in a marina would be the entry/egress route to/from the sea or river.
Cleopatra likely traveled from Alexandria to Memphis by following the River Nile. This route would have involved sailing south along the river, passing through major cities along the way such as Canopus, Rosetta, and Cairo. The journey would have taken several days and would have allowed Cleopatra to observe the abundant agriculture and trade along the riverbanks.