Alligator Reef

Alligator Reef is a barrier reef out from Islamorada in the Florida Keys, a decent boat ride offshore. A lighthouse tower marks the shallow reef, and the shade of its steel supports draws thousands of fish, including big schools of grey snapper and barracuda.

The reef is named after the ship Alligator, which sank in the 1800s. All that remains of it is a mound of ballast stones, which is covered in fish, with purple sea fans around the tower.

A short boat ride east leads to a mini wall with a ledge running north to south, in about 20 feet (6.1 metres) of water. Sergeant majors, yellowtail snapper, bar jacks and grunts gather under the ledge, and at around 15 feet (4.6 metres) there are midnight parrotfish, grouper, amberjack, a nurse shark, rock beauty and French angelfish. A hammerhead shark has been seen here on rare occasions. Water flowing over the reef is clear and blue, which gives excellent visibility.