Chesapeake Country’s Skyline Drive — with boats, not cars. That’s how Dave Linthicum sees the Patuxent River, which runs by his front door. Ask him why, and off his tongue rolls a list of Patuxent River glories. It’s lovely, for one, he says, with a quiet beauty that creeps up on you like fog. The Patuxent is historic. Humans have lived on its shores for 10,000 years, leaving their relics and place markers. Native Americans wrote their chapters of history on the land,...