Outdoor fun in Cancun is all about enjoying the warm, clear Caribbean Sea. Nearly every kind of watersport is available, from windsurfing and sailing to fishing and scuba diving. The easiest way to rent gear or find an operator is through your hotel—many of the larger properties have a watersports crew on-site. First-class golf courses, health clubs and tennis courts are also available for anyone who tires of the ocean.
Beaches
The Caribbean side of the Hotel Zone is justly famous for gorgeous white-sand beaches, but these aren't necessarily the best places to swim—the surf can pound mercilessly, and the undertow can be treacherous. Swim only where you see the water-safety pennant system: A white flag means the swimming is excellent, green signifies good or normal conditions, yellow means you should use caution, and black or red means conditions are unsafe. If you don't know what the water conditions are, don't swim. The safest place for swimming is along the northern shore of the island, facing Bahia de Mujeres.
All beaches in Mexico belong to the government and are therefore public. Once you get onto the beach, you can walk in either direction for as long as you want. Legally, you can use the beach in front of any of the resort hotels and no one can ask you to leave. However, you are not entitled to use any of the facilities provided by the hotel. Several of Cancun's beaches, including those at Playa Tortugas and Playa Delfines, have services that are available to everyone.
Boating & Sailing
You can rent all sorts of watercraft—Hobie Cats and Sunfish, for instance—to play in the sea. Sailboarding is especially popular, and equipment can be rented from seaside vendors at Playa Tortugas. Expect to pay about US$60 for a sailboard (add US$60 or so for lessons). The calm waters of Nichupte Lagoon make it a popular spot to water-ski. And you can literally get a bird's-eye view of the Hotel Zone while parasailing behind a boat.
Many of the major hotels have their own watersports rental facilities. Several independent marinas also specialize in rentals and deep-sea fishing charters.
Golf
There are plenty of courses to keep golfers occupied in Cancun. Official golf information is available from the Cancun Golf Association at http://www.cancungolf.org.
Scuba & Snorkeling
Almost all of Cancun's resorts rent snorkeling masks and fins, and they are complimentary for guests of the all-inclusive hotels. Although the underwater scenery isn't as stunning as that around Cozumel, you'll be surprised by the clarity of the water and the quantity of sea creatures. Snorkelers may want to join an excursion to one of the reefs off the north shore of the island. A popular dive site is the Manchones Reef, which is about 5 mi/8 km northeast of the island—close to Isla Mujeres. Divers and snorkelers also may want to explore the starting point of the Palancar Barrier Reef at Punta Nizuc, near the southern end of the Cancun Hotel Zone.
At Xcaret and at Garrafon Park on Isla Mujeres, you can try snuba—diving attached to a 20-ft-/6-m-long air hose that gives you more flexibility than snorkeling but doesn't require certification. The cost is about US$35.