Carysfort Reef Light

Carysfort Reef Lighthouse is one of the Florida Keys' most historically significant and ecologically important dive sites — a massive iron screw-pile lighthouse that has guided ships through the treacherous upper Keys reef since 1852 and now stands above one of the most productive sections of the Florida Keys National Marine Sanctuary's reef system. The lighthouse structure itself is a remarkable piece of 19th-century engineering — a skeletal iron framework rising from the reef on screw piles anchored into the coral limestone, a design pioneered specifically to withstand the hurricane conditions of the Florida Keys without requiring a solid masonry foundation. The underwater environment surrounding the lighthouse base extends to approximately 18 meters (60 feet) on the outer reef margins, with the spur-and-groove coral formations that characterize the upper Keys barrier reef creating excellent diving topography in all directions from the structure. The lighthouse's iron legs and supports, colonized over decades by corals and encrusting organisms, have become reef structures in their own right — providing additional hard substrate and structural complexity that concentrates fish and invertebrates in the immediate vicinity of the structure. Large nurse sharks rest in the structural shadows of the lighthouse base. Dense schools of grunt and snapper pack the areas between the spur formations. Hawksbill sea turtles feed on sponges throughout the reef structure, and green sea turtles graze on algae in the shallower zones. The Carysfort Reef area is known historically as one of the richest and most extensive reef sections in the upper Keys, though like all Florida Keys reefs it has experienced the stresses of bleaching, disease, and storm damage over the decades. Boat access from Key Largo operators, with Carysfort frequently included in upper Keys dive itineraries.