You can spend a day in Paris Bry-sur-Marne (with return to Paris by boat). Leaving the port Bastille in Paris, the boat lets you discover all the charms of the Marne, arriving for lunch at the famous tavern "At Gégène" in Joinville-le-Pont.
http://www.canauxrama.com/marne.htm
http://www.tourisme-valdemarne.com/loisirs-activites/croisieres.html
The port has four electric boats for daily rent (May 1 to September 30) for a tour along the river. You will pass under the bridges and admire the taverns, barges and greenery.
Capitainerie de Joinville- le-Pont, 2, quai Gabriel-Péri
http://www.ville-joinville-le-pont.fr/Port-de-plaisance,169.html
http://www.ville-joinville-le-pont.fr/Location-de-bateaux-electriques.html
http://www.ville-joinville-le-pont.fr/-Port-de-plaisance-.html
The Nogent sur Marne’s marina is one of the largest in the Paris region.
http://www.tourisme-nogentsurmarne.fr