I live on a houseboat just after paris in Meudon, facing Boulogne, we go paddle and swiming with the kids since they are 5 years old. The thing is to avoid going to the river the days after big rains. It is a very pleasant area along the Saint Germain Island (bras mort de l’Île Saint Germain)
> and every summer, young people, possibly a little drunk, jump into the water as a dare from bridges near Notre-Dame
After ending high school exams in 1993, we jumped into the Seine from Pont de Neuilly. I suppose this sort of antics have been going on since times immemorial and without counting bacteria beforehand... But I'm glad the river has cleaned up !
My first impression upon hitting the water: 1 - it is actually water (I expected mud !), 2 - wow, there is actually current and the shore goes by rather fast... No problems of any sort.
Anyway, it is fun - do it, and have a spotter to check for ships !
when I was a kid, I swam in the Seine one day out of young stupidity and the next day I got hives on my skin and it was very itchy. I learned the lesson and luckily in a couple of days I was back to normal. Some of the people in my group(that swam with me) had longer lasting problems.
The news is that it's now allowed / legal