Carysfort Reef Light, Historic lighthouse on Carysfort Reef, Florida Keys, United States

Carysfort Reef Light is a dark red skeletal iron tower, octagonal and pyramidal, 31 m tall, standing on an iron screw-pile foundation with a platform in about 1.4 m of water east of Key Largo. An octagonal two-storey keeper's house sits on the central platform; the lantern roof and house roofs are white. Large plates were added to the piles to spread the weight over the soft reef.

The structure was built between 1848 and 1852 under the direction of Lieutenant George Meade, who applied groundbreaking engineering techniques to achieve stability on the coral reef. His innovative design became a model for other lighthouses in challenging locations.

The reef takes its name from HMS Carysfort, a Royal Navy post ship that ran aground there in 1770. Before the tower, lightships guarded the spot: the Caesar from 1826 and the Florida from 1831. In 1837 Seminoles attacked keeper John Whalton and his helpers at their garden on Key Largo, killing Whalton and one helper.

The lighthouse stands in open water on Carysfort Reef, about six nautical miles east of Key Largo, and cannot be visited. Since 2014 a 12-metre metal beacon has marked the reef about 460 metres to the northeast, flashing three white blinks every 60 seconds. Boaters should note the shallow reef and strong currents.

Between 1833 and 1841, roughly 324 shipwrecks occurred on the reef where the lighthouse stands, with 63 happening directly at Carysfort Reef. This alarming tally shows how dangerous the waters were before the lighthouse was built.