PARIS — The world’s most romantic river traces a long arc through Paris, a stunning backdrop to complement the magnificent City of Lights. For centuries, lovers have walked along the Seine River, crossed its bridges, stared into its eddies and ripples. They’ve hung locks on its bridges as a sign of their love, they’ve watched the reflections of golden streetlights waver in the Seine’s current.

And while they do, they most definitely stay on shore. For all of the Seine’s well-deserved accolades as a beautiful, evocative river, only the truly foolish would actually venture into its waters. Because until very recently, the Seine was so toxic that the city didn’t even permit swimming.

Too filthy to support much marine life, it’s largely been, in effect, a picturesque garbage dump. Now, with the Olympics just days away, Paris officials are reaching the end of a years-long plan to clean the river, which will host the Opening Ceremony and, later, several Olympic swimming events. Early Wednesday morning, in an effort to show how clean the river is, Paris mayor Anne Hidalgo and others took a dip in the river's still-murky waters.

“The Seine is exquisite,” . “The water is very, very good. A little cool, but not so bad.

’' Like most Olympic plans, the cleanup of the Seine is a brash, audacious, expensive endeavor ...

and like so many Olympic plans, it might well collapse under the weight of its own vast ambitions. The Seine cleanup is part of France’s larger goa.