Key Largo, Florida, United States

French Reef

French Reef sits within the Florida Keys National Marine Sanctuary on the outer reef tract north of Molasses Reef and is well known for the number of swim-throughs, caves and ledges that cut into the coral platform. The most famous formation, Christmas Tree Cave, is a vertical chimney decorated with sponges and small invertebrates that exits onto the deeper reef around 12 metres. Other popular spots include Hourglass Cave and the White Sand Bottom Cave. Depths run from around 4 metres on the inner reef flat to 14 metres on the seaward slope, with sandy patches that host garden eels and southern stingrays. Goliath grouper, Nassau grouper, queen angelfish, spiny lobster and green and spotted moray eels are common residents, and divers regularly see hawksbill and loggerhead turtles working the reef. The site is fully moored under sanctuary regulations. Visibility is best in calm summer weeks; tidal currents can be felt along the outer wall but are usually manageable for novice divers.