Canal beneath Pont Morland (48.84694,2.36578); every person on this boat (that we saw) was a women, and every one seemed to be a heavy smoker.
Following the Seine upstream for a bit, we discovered a canal! With a lock! And a boat going up into…the Bassin de l’Arsenal, where pleasure boats (that are not very tall) moor. It is the modified waterway that used to bring Seine water to the moat around the Bastille.