Motorized transport of some sort is necessary, as sights are somewhat spread out. Public buses are good, and taxis relatively inexpensive. Renting a car is an unnecessary expense.

Here's our highly selective list of the very best things to see and do.

CANCÚN CONVENTION CENTER. This strikingly modern venue for cultural events is the jumping-off point for a 1-km-long (½-mi-long) string of shopping malls that extends west to the Presidente Inter-Continental Cancún. In the Convention Center complex itself, Inter Plaza has 15 restaurants, 21 boutiques, a bank, and several airline offices. Blvd. Kukulcán Km 9, PHONE: 98/83-01-99.

The National Institute of Anthropology and History, a small museum on the ground floor of the Convention Center, traces Maya culture with a fascinating collection of 1,000- to 1,500-year-old artifacts collected throughout Quintana Roo. Blvd. Kukulcán Km 9, PHONE: 98/83-03-05. COST: About $3, free Sun. Tues.-Sun. 9-7. Guided tours in English, French, German, and Spanish.

EL CENTRO (Downtown Cancún). Markets offer a glimpse into a more provincial Mexico. The main street, Avenida Tulum, is easily recognizable for the huge seashell sculpture in the roundabout, which adds drama to the city when lit up at night. Many restaurants and shops are located along this street. Ki Huic is the largest crafts market in Cancún. If you're looking for shopping bargains, however, you'll generally find better prices on the parallel Avenida Yaxchilán, particularly in Mercado Veinteocho (Market 28). Just off Avenida Yaxchilán and Sunyaxchén, this is the hub of downtown, filled with shops and restaurants frequented by locals.

ISLA MUJERES. Isla Mujeres (ees-lah moo-hair-ayce) has a magic all its own that helps it defy change. This tiny, fish-shape island 8 km (5 mi) off Cancún is a tranquil alternative to its bustling western neighbor. Only about 8 km (5 mi) long by 1 km (½ mi) wide, Isla has flat sandy beaches on its northern end and steep rocky bluffs to the south. It is a peaceful island retreat with a rich history and culture centered on the sea. Speedboats and passenger ferries run between Isla and Cancún.

RUINAS DEL REY (Ruins of the King). Large signs on the Zone's lagoon side, roughly opposite the Playa de Oro and El Pueblito hotels, point out these small ruins, which have been incorporated into the Caesar Park Beach & Golf Resort complex. Skeletons interred both at the apex and at the base indicate the site may have been a royal burial ground. Blvd. Kukulcán Km 17, PHONE: no phone. COST: About $3, free Sun. Daily 8-5.

TULUM. The spectacle of Tulum's limestone temples against the blue-green Caribbean waters is nothing less than riveting. This is the largest coastal city that the Maya built, and the only Maya city known to have been inhabited when the conquistadors arrived. Unfortunately, you'll share the site with roughly half the tourist population of Quintana Roo on any given day, even if you arrive early. The first significant structure you'll see is the two-story Temple of the Frescoes, to the left of the entrance. The largest and most famous building, the Castillo, looms at the edge of a 40-ft limestone cliff just past the Temple of the Frescoes. 2 km (1 mi) south of Tankah, 130 km (81 mi) south of Cancún.

Beaches

Cancún has a wonderful variety of beaches: Those who thrive on the resort atmosphere will probably enjoy Playa Chacmool and Playa Tortugas on the bay side, which is calmer, if less beautiful, than the windward side. On the north end of Isla Mujeres, Playa Norte (or Playa Cocoteros) offers handsome sunset vistas.

Golf

POK-TA-POK. Cancún's main course has fine views of both sea and lagoon, and its 18 holes were designed by Robert Trent Jones, Sr. Greens fees are $70 ($55 after 2 PM); carts are $25. Blvd. Kukulcán between Km 6 and Km 7, PHONE: 98/83-12-30. www.cancungolfclub.com

CAESAR PARK BEACH & GOLF RESORT. There is an 18-hole championship golf course at the Ceasar Park Resort. Greens fees are $95 ($75 for hotel guests), and carts are included. Blvd. Kukulcán Km 17, PHONE: 98/81-80-16.

HOTEL MELIÁ CANCÚN. The 18-hole executive course (par 53) at the Hotel Meliá Cancún shares the property's beautiful ocean views. The greens fee is about $20. Blvd. Kukulcán Km 12, PHONE: 98/85-11-60.

Fishing

Some 500 species of tropical fish, including sailfish, bluefin, marlin, barracuda, and red snapper, live in the waters adjacent to Cancún. Deep-sea fishing boats and gear may be chartered from outfitters for about $350 for four hours, $450 for six hours, and $550 for eight hours. Charters generally include a captain, a first mate, gear, bait, and beverages.

MARINA DEL REY. Blvd. Kukulcán Km 15.5, PHONE: 98/83-05-54.

MUNDO MARINA. Blvd. Kukulcán Km 5.5, PHONE: 98/83-04-42.

AQUA TOURS. Blvd. Kukulcán Km 6, PHONE: 98/83-02-27.

BARRACUDA MARINA. Blvd. Kukulcán Km 14, PHONE: 98/85-34-44.

Snorkeling and Scuba Diving

Snorkeling is best at Parque Nizuc, Punta Cancún, and Playa Tortugas, although you should be especially careful of the strong currents at the last. You can generally rent snorkeling gear for $10 per day from many of the scuba-diving places, and most hotels and resorts have their own gear for rent.

BARRACUDA MARINA. Barracuda Marina has a two-hour Wave Runner jungle tour through the mangroves, which ends with snorkeling at the Punta Nizuc coral reef. Blvd. Kukulcán Km 14, PHONE: 98/85-24-44.

Scuba diving has gained in popularity in Cancún. A word of caution about one-hour courses offered as a freebie by the resorts: this does not prepare you to dive in the ocean, no matter what the high-pressure concession operators tell you. The secret of a good scuba company is personal attention. Ask to meet the dive master and check out the company's equipment and certifications thoroughly.

SCUBA CANCÚN. Scuba Cancún specializes in diving trips and offers NAUI, CMAS, and PADI instruction. It's operated by Luis Hurtado, who has more than 35 years of experience. Blvd. Kukulcán Km 5, PHONE: 98/83-10-11.

BLUE PEACE DIVING. Two-tank dives with NAUI, SSI, and PADI instruction are offered here. Blvd. Kukulcán Km 16.2, PHONE: 98/85-14-47.