Six working lighthouses still mark the navigational hazards of Narragansett Bay, more per square mile than any comparable estuary on the Atlantic coast. Rose Island Light, decommissioned in 1971 and restored by volunteers in 1993, now serves as the nation's only operational lighthouse offering overnight keeper programs. Castle Hill Light, a conical granite tower commissioned in 1890, warns vessels away from the rocky shoals at the mouth of the East Passage. Lime Rock Light, built in 1854, gained fame through keeper Ida Lewis, who performed at least eighteen documented rescues between 1858 and 1906 and became the first woman awarded the Congressional Gold Lifesaving Medal. The bay's lighthouse network reflects three centuries of maritime traffic evolution. Newport Harbor Light, established in 1823 and rebuilt in 1842, guided the China trade clippers into the colonial port. Conimicut Light, an 1868 cast-iron sparkplug tower on a caisson foundation, marked the Providence River shipping channel for coal barges and steamships. Plum Beach Light, completed in 1899, stands on a granite pier in the West Passage, its fixed red light still operational under Coast Guard automation. Each structure employed distinct architectural solutions to the bay's variable geology — bedrock foundations for shoreline towers, caisson pilings for open-water stations. Narragansett Bay lighthouse cruise routes typically cover five to six towers during two-hour scenic passages, departing from Newport's historic wharves. Modern interpretive cruises combine lighthouse viewing with narration on colonial shipping routes, rum-running operations during Prohibition, and the transition from whale-oil lamps to Fresnel lenses. The bay's protected waters and relatively compact lighthouse constellation make it an ideal platform for comparative maritime architecture study. Several vessels offer morning departures timed to catch optimal eastward lighting on the granite and cast-iron facades. The lighthouse concentration stems from the bay's role as the primary deepwater harbor between New York and Boston. By 1900, fourteen lighthouses operated within the bay system, guiding passenger steamers, fishing fleets, and cargo vessels through fog, nor'easters, and the bay's notorious riptides. Today's six remaining towers represent the survivors of automation, storm damage, and shifting shipping channels. All continue active Coast Guard service, their solar-powered beacons visible from narragansett bay lighthouse cruise decks on clear evenings.