There have been quite a few improvements since I've lived in Paris (early 2000s). I've never really tried the Seine itself, but did quite a few swims in Marne

There have been quite a few improvements since I've lived in Paris (early 2000s). I've never really tried the Seine itself, but did quite a few swims in Marne (its tributary that flows in just outside the inner city limits) and the canals.