Most of the bateaux mouches, literally flyboats, that ply the Seine are little more than tourist barges. Whether watching the hordes aboard cheers or annoys largely depends on one’s mood and the weather. Valuable as tourists dollars are, I find boats that carry humbler cargos than waving rubberneckers far more precious, and uncommon. They are a happy break from the service-industry vibe of most river traffic, with its glass roofs and floodlight flanks, and remind that for the bulk of its human history, the Seine has been a working waterway. The blanchiesse barges may have gone, but sand and coal remain.