In blue-sky summer days, superyachts tie up near the luxury condos. In winter storms, the huge regional food distribution center becomes part of the North Atlantic. Once famed for pollution, this stretch of coast now is clean enough for everything from whales to whimbrels and the islands are public parks. South Boston's Seaport has been rebuilt as Manhattan on a mudflat, with yet more condos for the wealthy plus thousands of offices and biomedical labs but no libraries nor schools nor almost anything to welcome people of color or anyone on a tight budget. But the city is developing thoughtful plans to guard the shore against sea-level rise and the bigger storms arriving. Welcome to today's Boston Harbor, in these snapshots of wandering the waterfront on foot and kayak.