Palancar Reef

Palancar is the best known of the reefs that made Cozumel one of the world's great diving destinations. It runs along the southwest coast of the island for several kilometers and is part of the Arrecifes de Cozumel National Park, protected since 1996, which covers the reefs off the island's southern half and belongs to the Mesoamerican Reef, the second-largest reef system in the world.

The reef is not one site but a series of dives with names like Palancar Gardens, Palancar Caves and Horseshoe. Deeper down, huge coral buttresses rise from the sand, cut by canyons, swim-throughs and tunnels, and the reef's edge drops into deep blue water. The shallower sections are within reach of snorkelers on boat trips. The current along the coast is usually steady, so most dives here are drift dives: the boat drops you at one end and picks you up where the current takes you.

You can expect turtles, eagle rays, moray eels, groupers and huge sponges, though Cozumel's reefs, like others in the Caribbean, have suffered in recent years from coral disease and bleaching. That makes following the park's rules, from not touching the coral to using no regular sunscreen, more important than ever.