Cayo Largo sits on the edge of a long, healthy coral reef — the southern barrier of the Canarreos Archipelago — and is one of the better places to dive in the Caribbean. The reef wall drops off close to shore, giving easy access to drop-offs, swim-throughs, and a number of small wrecks. Visibility is regularly 25 to 30 metres.
The single dive centre on the island, run from the marina, offers two-tank morning dives, snorkelling trips, and PADI courses. Highlights include the Cabezo de las Lisas (a coral mound at 20m popular with reef sharks), the Tete wreck dive, and the wall at Cabezo Rico. Beginners can snorkel directly from Sirena and Paraíso — coral heads are within easy reach of the beach.