Chankanaab National Park & Faro Celerain Ecological Reserve (Punta Sur)

Chankanaab National Park (www.cozumelparks.com), off the Carretera Costera Sur at Km 9, is the pride of many islanders. In Mayan, Chankanaab means "little sea," which refers to a beautiful land-locked pool connected to the sea through an underwater tunnel -- a sort of miniature ocean. Snorkeling in this natural aquarium is not permitted, but the park itself has a beach for sunbathing and snorkeling. Arrive before 9am to stake out a chair and palapa before the cruise-ship crowd arrives. The snorkeling is also best before noon. The park has bathrooms, lockers, a gift shop, several snack huts, a restaurant, and a palapa for renting snorkeling gear.

You can also swim with dolphins here. Dolphin Discovery (tel. 800/293-9698; www.dolphindiscovery.com) has several programs for experiencing these sea creatures. These are popular, so plan ahead -- you should make reservations well in advance. The surest way is through the website -- make sure to pick the Cozumel location, as there are a couple of others on this coast. There are three different programs for swimming with dolphins. The Dolphin Royal Swim costs $129 and features close interaction with the beautiful swimmers. There are also swim-and-snorkel programs for under $100 that get you in the water with these creatures. The park is open daily from 9am to 5pm and lies south of town, just past the Fiesta Americana Hotel. Taxis run constantly between the park, the hotels, and town (about 100 pesos from town for up to four people).

Faro Celerain Ecological Reserve (admission $10), also called Punta Sur, is an ecological reserve at the southern tip of the island that includes the Columbia Lagoon. A number of crocodiles make the lagoon their home, so swimming is not only a bad idea, it's not allowed. The only practical way of going out to the lighthouse, which lies 8km (5 miles) from the entrance, is to rent a car or scooter; there's no taxi stand, and usually few people. At the entrance to Punta Sur, you'll find a reggae beach bar and a sea turtle nesting area. The lovely beaches just in front are kept as natural as possible, but be cautious about swimming or snorkeling here depending on the winds and currents. Regular hours are daily 9am to 6pm. If you have a rental car, getting here is no problem, and this is usually a great place to get away from the crowds and have a lot of beach to yourself. Occasionally, boat tours of the lagoon are offered. Ask at the information office.

Anatomy of the Coral Reef

Corals are polyps, tiny animals with hollow, cylindrical bodies that attach by the thousands to hard surfaces of the sea floor. The polyps extract calcium carbonate from the seawater to create hard, cup-shaped skeletons that assume an endless variety of shapes and sizes. These massive limestone structures shelter nearly one-fourth of all marine life. The soft, delicate polyps retreat into their skeletons during the day, but their protruding tentacles can be seen when they feed at night.

Two distinct types of coral formations dominate Cozumel's waters. Bases of the less developed platform reefs, such as Colombia Shallows, Paradise, and Yucab, are rarely more than 9 to 15m (30-49 ft.) in depth. Edge reefs are more complex structures built up over many millennia, and their layered structures peak high above the edge of the drop-off, extending as much as 55m (180 ft.) below the surface. These are found mostly in the south; examples include Palancar, Colombia Deep, Punta Sur, and Maracaibo.

Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.