Boston Harbor holds thirty-four islands, and within living memory its water ranked among the dirtiest in the United States. A 1985 federal court order forced a cleanup that ran for two decades and consumed roughly $4.5 billion in public money. The harbor that now carries Boston Tiki Boat Tours is a direct product of that judgment — swimmable, fishable, and crowded each summer with ferries, tugs, schooners and sightseeing boats. Rowes Wharf carries the name of John Rowe, the merchant who held this frontage in the 1760s and who owned the Eleanor, one of three ships boarded in December 1773. The red-brick arch that frames the water today is newer than it looks: Skidmore, Owings & Merrill completed it in 1987, a deliberate reopening of a waterfront that the elevated Central Artery had walled off for three decades. Its ground floor still works as a public passage between Atlantic Avenue and the water's edge. Boston Tiki Boat Tours tours work this same stretch of shoreline, a short walk from Long Wharf, where packet ships once cleared for Liverpool. The thatched pontoon itself is an import. Builders on Florida's Gulf Coast began mounting circular palm-roofed bars onto twin-hull platforms in the mid-2010s, and the form travelled north until it reached New England. The logic holds here for a reason the builders never planned: the inner harbor is shallow, hooked shut by islands, and almost always flat. A slow, low, open-sided vessel makes sense in this basin in a way it never would off Cape Ann, which is why the Boston Harbor tiki boat cruise took hold where other novelty craft did not. What the water returns is a reading of the city that no sidewalk offers. From the mouth of the Fort Point Channel the Financial District stacks up behind the Custom House clock tower, finished in 1915 and the tallest structure in Boston for nearly half a century. Northward stand the masts of USS Constitution, launched in 1797 and still a commissioned warship, berthed at the Charlestown Navy Yard. Southeast, the granite pentagon of Fort Independence holds Castle Island, and nine miles out Boston Light has marked Little Brewster Island since 1716 — the oldest light station site in the country. Container ships bound for Conley Terminal cross the same water, proof that this is a working port and not a stage set. A Boston Harbor sightseeing cruise threads those landmarks in sequence; Boston Tiki Boat Tours tickets put a thatched roof over the same sightline.