The water is barely above ten degrees Celsius, but that's "very comfortable" for the fifteen or so swimmers who are taking a dip in the Seine at L'Ile-Saint-Denis, downstream from Paris. The group known as the 'Ourcqs polaires' are used to swimming in the the Ourcq canal, north of the capital, but are taking advantage of a mammoth effort to clean the Seine -- due to host the Olympic triathlon and distance swimming events this summer -- to take their hobby to the famed river. "There's something really powerful and very, very pleasant it," says a member of the group. IMAGES AND SOUNDBITES ARRANGED IN SEQUENCES N°34QN867