Guide · what lives on the reefs
Cancun Marine Life
Cancun marine life is classic Caribbean reef life at the northern end of the Mesoamerican Reef: turtles on most dives, eagle rays and nurse sharks, big schools of grunts and snappers, and a few seasonal visitors worth planning around.
The reefs off Cancun, Isla Mujeres and Puerto Morelos are the northern end of the Mesoamerican Reef, the largest reef system in the Western Hemisphere, which runs south past Belize to Honduras. The marine life here is the same family of Caribbean species you'd see further south, in shallower, brighter water. This guide covers what divers see most, where, and when.
Sea turtles
Turtles are the animal most people remember from diving here. Green turtles graze the seagrass beds beside reefs like Chitales and Punta Nizuc and rest on the reef between meals. Hawksbill turtles, with their pointed beaks and overlapping shell plates, feed on sponges on the reef itself. Loggerheads, with big heads, are seen less often, more on the outer sites. In summer, females come ashore to nest on beaches along this coast, and nesting beaches are protected. See them up close on Manchones Reef and the Punta Cancun reefs.
Rays and sharks
Southern stingrays lie half-buried in the sand channels, and you'll see their feeding pits on most reefs. Spotted eagle rays fly over the sand and along the reef edges, and they gather around the deeper wrecks, such as the C-58 and C-55, from about late November through the winter. Nurse sharks may rest under ledges by day and are calm with divers. They are not the famous "sleeping sharks": the sharks found resting in the Cave of the Sleeping Sharks in the 1970s were mainly Caribbean reef sharks.
Two bigger shark encounters happen near Cancun, though not on the reefs on this site. Whale sharks gather north-east of Isla Mujeres in summer, roughly mid-May to mid-September. They are seen on snorkelling tours only: scuba is not allowed with them. Bull sharks visit Playa del Carmen, further south, in winter, on specialised dives for experienced divers.
Reef fish
- Grunts and snappers: French grunts, white grunts, schoolmasters and yellowtail snappers form the big yellow schools under ledges and around coral heads.
- Parrotfish: stoplight, queen and rainbow parrotfish crunch algae off the coral. You can often hear them.
- Angelfish and butterflyfish: queen, French and grey angelfish, plus foureye and banded butterflyfish.
- Predators: great barracuda hang still near the surface, and groupers and jacks patrol the deeper reefs and wrecks.
- Hiders: green and spotted moray eels, spiny lobsters, squirrelfish and glasseye snappers in the holes.
- Lionfish: an invasive species in the Caribbean since the 2000s. Some local operators are allowed to spear them, and you may see them on restaurant menus.
Corals and the state of the reef
The reefs have brain and boulder corals, sea fans, sea rods and sponges, plus elkhorn and staghorn coral in shallow water, both of them branching corals that have declined badly across the Caribbean. The reefs here have been through a lot: Hurricane Wilma in 2005, coral bleaching in hot years, seasonal sargassum seaweed since the 2010s, and from 2018 the stony coral tissue loss disease, which killed many brain and star corals in the Mexican Caribbean. You'll see dead coral beside healthy patches. Fish life has held up better, and restoration groups are growing and replanting corals in several areas.
At night
Night dives on shallow reefs like Manchones show a different set of animals: octopus hunting in the open, lobsters and crabs out of their holes, parrotfish asleep in mucus cocoons, and bioluminescent plankton that sparkle when you wave a hand with your light off. Most shops run night dives on request on the easier reefs.
Seasons that matter
| What | When (approximate) | Where |
|---|---|---|
| Eagle rays at the wrecks | Late November to March | C-58, C-55 and other deep sites |
| Turtle mating | About May to July | Reported around Punta Sur |
| Turtle nesting | Summer | Beaches (not a dive) |
| Whale sharks | About mid-May to mid-September | Offshore north-east of Isla Mujeres; snorkel only |
| Bull sharks | About November to March | Playa del Carmen, south of this area |
Watching wildlife responsibly
- Keep a few metres from turtles, rays and sharks, and never block a turtle's way to the surface.
- No touching, riding, feeding or chasing. It's against park rules and it stresses the animals.
- Don't use flash at close range on resting animals.
- Keep your fins off the coral and the sand near it.
Ready to go looking? Use the dive site map to choose sites, or start with the Cancun dive sites for beginners.
Seasons are approximate and change from year to year. Wildlife sightings are never guaranteed.