Parisians flocked to the 19th arrondissement on Sunday afternoon to enjoy the one-off opportunity to swim in the Bassin de la Villette, which connects the Canal de l'Ourcq with the Canal Saint-Martin.
And it really was a one-off, as swimming there has been forbidden since 1923 and comes with the risk of a €38 fine.
The day was organized by the French Swimming Federation (FFN), and saw scores of swimmers race along the man-made lake in the early afternoon.
By around 3pm, the Parisians took the plunge after reports that the waterway would be temporarily opened to the public.
Those at the scene reported that police initially tried to keep people from taking the plunge, but before long the water was filled with swimmers, toys, and one striking pink inflatable flamingo.
Police kept close by, ensuring that swimmers didn't jump off the bridges, though many took the leap of faith anyway.
And the good news is that Paris Mayor Anne Hidalgo has said that she aims to open the swimming hole up to the public from next summer, reported Le Parisien newspaper.
Here's how it looked on Sunday: