A rowing team from the local club nautico just pulled by and they're really good.
It goes "whop" when they flatten the oars at the end of the stroke in perfect synchronicity. And "whirr" when the seats slide on their bearings. Humans trained to work like machines, propelling a boat.
Spanish boating clubs seem pretty active, offering a much greater variety of water sports than in Italy, where club nautico mostly means an affordable place to keep a sailboat.