Islamorada, Florida, United States

Alligator Reef

Alligator Reef sits four nautical miles off Islamorada on the outer reef tract and is marked by Alligator Reef Light, an 1873 screw-pile cast-iron lighthouse listed on the National Register of Historic Places. The reef takes its name from USS Alligator, a US Navy schooner lost on the reef in November 1822 while pursuing pirates; the ship was deliberately blown up to prevent capture and timbers and ballast can still be found scattered in the sand. The modern site is a moored Sanctuary Preservation Area within the Florida Keys NMS, with spur-and-groove formations dropping from about 4 metres on the inner flat to 12 metres on the seaward edge. Divers regularly see green and hawksbill turtles, southern stingrays, Caribbean reef squid in season, queen angelfish, midnight parrotfish and large schools of yellowtail snapper. Currents are usually moderate and visibility opens up significantly when the Gulf Stream pushes in close, typically in late summer and fall.