The reef system running along the Atlantic side of the Abaco cays is one of the most extensive in the Bahamas. The water is clear and shallow enough close to shore for good snorkelling without equipment beyond a mask and fins, and deeper reef diving is available through several operators based in Marsh Harbour and Hope Town.
The USS Adirondack wreck off Man-O-War Cay is a popular dive site — the Union Navy sloop ran onto the reef in 1862 and has sat in about 30 feet of water ever since, now encrusted with coral and home to large schools of fish. Elkhorn and staghorn coral formations on the outer reef are in reasonable condition by Bahamian standards, with nurse sharks, eagle rays, and sea turtles regular sightings. Dive operators in Marsh Harbour run day trips to the best sites; certification is required for the deeper dives.