Active Pursuits

Many beachside hotels offer watersports concessions that rent rubber rafts, kayaks, and snorkeling equipment. On the calm Nichupté lagoon are outlets for renting sailboats, jet skis, sailboards, and water skis. Prices vary and are often negotiable, so check around.

Deep-Sea Fishing

You can arrange a day of deep-sea fishing at one of the numerous piers or travel agencies for $220 to $360 (£121-£198) for 4 hours, $420 (£231) for 6 hours, and $520 (£286) for 8 hours for up to four people; for up to eight people, the prices are $420 (£231) for 4 hours, $550 (£303) for 6 hours, or $680 (£374) for 8 hours. Marinas will sometimes assist in putting together a group. Charters include a captain, a first mate, bait, gear, and beverages. Rates are lower if you depart from Isla Mujeres or from Cozumel -- and frankly, the fishing is better closer to those departure points.

Scuba & Snorkeling

Known for its shallow reefs, dazzling color, and diversity of life, Cancún is one of the best places in the world for beginning scuba diving. Punta Nizuc is the northern tip of the Gran Arrecife Maya (Great Mesoamerican Reef), the largest reef in the Western Hemisphere and one of the largest in the world. In addition to the sea life along this reef system, several sunken boats add a variety of dive options. Inland, a series of caverns and cenotes (wellsprings) are fascinating venues for the more experienced diver. Drift diving is the norm here, with popular dives going to the reefs at El Garrafón and the Cave of the Sleeping Sharks -- although be aware that the famed "sleeping sharks" have departed, driven off by too many people watching them snooze.

A variety of hotels offer resort courses that teach the basics of diving -- enough to make shallow dives and slowly ease your way into this underwater world of unimaginable beauty. One preferred dive operator is Scuba Cancún, Bulevar Kukulkán Km 5 (tel. 998/849-4736; www.scubacancun.com.mx), on the lagoon side. Full certification takes 3 days and costs $410 (£226). Scuba Cancún is open daily from 7am to 8pm, and accepts MasterCard and Visa. For certified divers, Scuba Cancún also offers diving trips in good weather to 18 nearby reefs, as well as to Cenotes Caverns (9m/30 ft.) and Cozumel. The average dive is around 11m (36 ft.), while advanced divers descend farther (up to 18m/60 ft). Two-tank dives to reefs around Cancún cost $68 (£37); those to farther destinations cost $140 (£77). Discounts apply if you bring your own equipment. Dives usually start around 9:30am and return by 1:30pm. Snorkeling trips cost $27 (£15) and leave every afternoon at 1:30pm and 4pm for shallow reefs about a 20-minute boat ride away.

The largest dive operator is Aquaworld, across from the Meliá Cancún at Bulevar Kukulkán Km 15.2 (tel. 998/848-8327; www.aquaworld.com.mx). It offers resort courses and diving from a man-made anchored dive platform, Paradise Island. Aquaworld has the Sub See Explorer, a boat with picture windows that hang beneath the surface. The boat doesn't submerge -- it's an updated version of a glass-bottom boat -- but it does provide nondivers with a look at life beneath the sea. This outfit is open 24 hours a day and accepts all major credit cards.

Besides snorkeling at El Garrafón Natural Park, travel agencies offer an all-day excursion to the natural wildlife habitat of Isla Contoy, which usually includes time for snorkeling. The island, 90 minutes past Isla Mujeres, is a major nesting area for birds and a treat for nature lovers. You can call any travel agent or see any hotel tour desk to get a selection of boat tours to Isla Contoy. Prices range from $45 to $70 (£25-£39), depending on the length of the trip, and generally include drinks and snorkeling equipment.

The Great Mesoamerican Reef also offers exceptional snorkeling opportunities. In Puerto Morelos, 37km (23 miles) south of Cancún, the reef hugs the coastline for 15km (9 1/3 miles). The reef is so close to the shore (about 460m/1,509 ft.) that it forms a natural barrier for the village and keeps the waters calm on the inside of the reef. The water here is shallow, from 1.5 to 9m (5-30 ft.), resulting in ideal conditions for snorkeling. Stringent environmental regulations implemented by the local community have kept the reef here unspoiled. Only a select few companies are allowed to offer snorkel trips, and they must adhere to guidelines that will ensure the reef's preservation. Cancún Mermaid (tel. 998/843-6517; www.cancunmermaid.com) is considered the best -- it's a family-run ecotour company that has operated in the area since the 1970s. It's known for highly personalized service. The tour typically takes snorkelers to two sections of the reef, spending about an hour in each area. When conditions allow, the boat drops off snorkelers and then follows them along with the current -- an activity known as "drift snorkeling," which enables snorkelers to see as much of the reef as possible. The trip costs $50 (£28) for adults, $35 (£19) for children, and includes boat, snorkeling gear, life jackets, a light lunch, bottled water, sodas, and beer, plus round-trip transportation to and from Puerto Morelos from Cancún hotels. Departures are Monday through Saturday at 9am. For snorkelers who just can't get enough, a combo tour for $30 (£17) more adds a bicycle tour to additional snorkeling destinations. Reservations are required at least 1 day in advance; MasterCard and Visa are accepted.

Jet-Ski Tours

Several companies offer the popular Jungle Cruise, which takes you by small boat or WaveRunner (you drive your own watercraft) through Cancún's lagoon and mangrove estuaries out into the Caribbean Sea and a shallow reef. The excursion runs about 2 1/2 hours and costs $55 (£30), including snorkeling equipment and bottled water. Many people prefer the companies offering two-person boats rather than WaveRunners, since they can sit side by side rather than one behind the other.

Jet-ski operators and names offering excursions change often. To find out what's available, check with a local travel agent or hotel tour desk. The popular Aquaworld, Bulevar Kukulkán Km 15.2 (tel. 998/848-8327), calls its trip the Jungle Tour and charges $55 (£30) for the 2 1/2-hour excursion, which includes 45 minutes of snorkeling time. It even gives you a free snorkel, but has the less desirable one-behind-the-other seating configuration. Departures are daily every hour between 8am and 3pm.

Dolphin Swims

On Isla Mujeres, you have the opportunity to swim with dolphins at Dolphin Discovery (tel. 998/877-0207 or 849-4757; www.dolphindiscovery.com). Groups of eight people swim with two dolphins and one trainer. Swimmers view an educational video and spend time in the water with the trainer and the dolphins before enjoying 15 minutes of free swimming time with them. Reservations are recommended, and you must arrive an hour before your assigned swimming time, at 10:30am, noon, 2pm, or 3:30pm. The cost is $139 (£76) per person for the Dolphin Royal Swim. There are less expensive programs that allow you to learn about, touch, and hold the dolphins (but not swim with them) starting at $79 (£43). Ferry transfers from Playa Langosta in Cancún are available.

La Isla Shopping Center, Bulevar Kukulkán Km 12.5, has an impressive Interactive Aquarium (tel. 998/883-0411, -0436, or -0413; www.aquariumcancun.com.mx), with dolphin swims and shows and the chance to feed a shark while immersed in the water in an acrylic cage. Guides inside the main tank use underwater microphones to point out the sea life, and even answer your questions. Open exhibition tanks enable visitors to touch a variety of marine life, including sea stars and manta rays. The educational dolphin program costs $65 (£36), while the dolphin swim is $135 (£74) and the shark-feeding experience runs $65 (£36). The entrance fee to the aquarium is $13 (£7.15) for adults, $9 (£4.95) for children, and it's open daily from 9am to 6pm.

Golf & Tennis

The 18-hole Pok-Ta-Pok Club, or Club de Golf Cancún (tel. 998/883-0871), is a Robert Trent Jones, Sr., design on the northern leg of the island. Greens fees run $105 (£58) for 18 holes including golf cart (discounted twilight fees), with clubs renting for $40 (£22). A caddy costs $20 (£11). The club is open daily from 6:30am to 6:30pm, accepts American Express, MasterCard, and Visa, and has tennis courts.

The Hilton Cancún Golf & Spa Resort (tel. 998-881-8016) has a championship 18-hole, par-72 course around the Ruinas Del Rey. Greens fees for the public are typically $199 (£109) for 18 holes and $149 (£82) for 9 holes; Hilton Cancún guests pay discounted rates of $149 (£82) for 18 holes, or $99 (£54) for 9 holes, which includes a golf cart. Low season and twilight discounts are available. Golf clubs and shoes are available for rent. The club is open daily from 6am to 6pm and accepts American Express, MasterCard, and Visa. The Gran Meliá Cancún (tel. 998/881-1100) has a 9-hole executive course; the fee is $53 (£29). The club is open daily from 7am to 3pm and accepts American Express, MasterCard, and Visa.

The first Jack Nicklaus Signature Golf Course in the Cancún area has opened at the Moon Palace Spa & Golf Club (tel. 998-881-6000; www.palaceresorts.com), along the Riviera Maya. The $260 (£143) greens fee includes cart, snacks, and drinks.

Horseback Riding

Cancún Mermaid (tel. 998/843-6517; www.cancunmermaid.com), about 30 minutes south of town at the Rancho Loma Bonita, is a popular option for horseback riding. Five-hour packages include 2 hours of riding through the mangrove swamp to the beach, where you have time to swim and relax. The tour costs $72 (£40) for adults and children. The ranch also offers a four-wheel ATV ride on the same route as the horseback tour. It costs $72 (£40) per person if you want to ride on your own, $55 (£30) if you double up. Prices for both tours include transportation to the ranch, riding, soft drinks, and lunch, plus a guide and insurance. Only cash or traveler's checks are accepted.