Cozumel is a drift diving island, and nearly everything else about diving here follows from that single fact. The Yucatán Current runs up the sheltered west side of the island from south to north, more or less all day, every day. Dive boats do not anchor and divers do not swim. You roll in, the group descends together, and the current carries you along the wall while the captain follows the bubbles and picks everyone up wherever they surface. The first time it happens it feels like cheating. Experienced divers who have spent their careers finning into current on a fixed mooring tend to spend the whole first dive grinning.
The reef itself is the northern end of the Mesoamerican Barrier Reef, the second largest reef system in the world, and it has been a Mexican national marine park since the 1990s. The named sites run down the leeward coast in a rough south-to-north order: Paradise Reef and Chankanaab Reef close to town and shallow, Santa Rosa Wall and Palancar in the middle where the drop-offs start, then Colombia and Punta Sur at the southern tip where the wall falls past 150 feet and the coral heads become cathedrals with tunnels through them. Palancar alone is four distinct dives — Gardens, Horseshoe, Caves and Bricks — which is why a week here does not repeat itself. Visibility routinely sits at 80 to 100 feet and often better, because the current is constantly flushing the reef with clean open-ocean water.
A standard day is a two-tank morning. Boats leave the hotel docks and the town piers between about 7:30 and 8:30, run twenty to forty-five minutes south depending on the site, dive deep first and shallow second, and are back by early afternoon. Afternoon single-tank trips work the shallower reefs near town, and night dives on Paradise Reef are the island's other signature, because the splendid toadfish that lives here is found nowhere else on earth and comes out after dark.
Two very different readers are looking at this page. If you are off a ship, the constraint is all-aboard time and nothing else. A two-tank morning fits an eight-hour call if the boat leaves on time, but the margin is thin, and independent operators who do not know your ship's schedule are the risk. If you are staying on the island, you can dive four or five days, take the afternoon slot, do a night dive and finish on the shallow reefs before you fly.
Two practical rules that apply to everyone. The marine park charges a per-person daily fee on top of your dive price, collected by the shop and handed to you as a dated wristband. And gloves are generally prohibited, touching or standing on coral is not allowed, and the reason is visible in the older photographs of these sites. Keep your hands to yourself and trim so your fins are not dragging.
