A 41m iron skeletal lighthouse standing in open water over a shallow reef, the most photographed structure in the Keys and one…A 41m iron skeletal lighthouse standing in open water over a shallow reef, the most photographed structure in the Keys and one of the best snorkels, with elkhorn coral, tarpon under the legs, huge barracuda, nurse sharks and permit. The lighthouse legs themselves act as a fish magnet. Built in 1873 and named for the USS Alligator, a schooner that hunted pirates and slavers and wrecked here in 1822, the crew blew her up to stop pirates salvaging her. Decommissioned in 2014 and now in the hands of a preservation trust fighting to keep it standing. Anchorage: Mooring buoys; anchor on sand well clear of coral. Islamorada marinas 4nm inshore. Hazards: No site-specific hazards noted, brief normally. Plus