Narragansett Bay unfolds across 147 square miles of tidal estuary between Rhode Island and Massachusetts, its waters threading past 30 islands and eight lighthouses that have guided vessels since the colonial era. The bay's strategic position made Newport a maritime powerhouse by 1639, its protected harbor sheltering trade routes and naval fleets for three centuries. Today the waterway holds the nation's oldest active lighthouse — Beavertail Light, commissioned in 1749 — and remains the proving ground where America's Cup defenders trained between 1930 and 1983. A scenic Narragansett Bay cruise departs from Bowen's Wharf, the same wharves where 18th-century packet ships loaded rum and spermaceti candles bound for European ports. Modern harbor tours navigate the East Passage, rounding Fort Adams — a 21-acre pentagonal fortress completed in 1857 that once held 2,400 troops and 468 cannons. The bay's tidal range averages four feet, creating currents that shift twice daily and carve channels between Conanicut Island, Prudence Island, and the mainland shore. Rose Island Lighthouse, decommissioned in 1971 and restored as a museum in 1993, marks the northern harbor entrance where wooden schooners still race each summer under spinnaker. The waterway's ecology supports winter flounder, blue crab, and migrating osprey that nest on channel markers from April through September. Sailing vessels follow routes past Castle Hill Lighthouse, a granite tower built in 1890 on a glacial moraine, and the Newport Bridge — a 11,248-foot suspension span opened in 1969 that connects Aquidneck Island to Jamestown. Harbor lighthouse tours often include narration on the bay's role in the Revolutionary War, when French and British fleets clashed off Point Judith in 1778, and the Gilded Age, when Vanderbilt and Astor yachts moored along the same waterfront that now hosts modern sailboats. Schooner cruises aboard traditional gaff-rigged vessels recall the bay's shipbuilding legacy — Newport yards launched over 300 vessels between 1740 and 1850, including privateers and slave-trade brigs. The Aquidneck, a 67-foot wooden schooner built in 1986, replicates designs from the 1920s and carries passengers on daytime and sunset sails that trace the America's Cup racing course. Evening departures showcase the bay at twilight, when the setting sun silhouettes the Claiborne Pell Bridge towers and illuminates the mansions along Ocean Drive, their lawns descending to seawalls that have withstood nor'easters since the 1890s.