Activities range from beachcombing to reef diving to archaeological excursions. Your kids will love visiting a crocodile farm or the aquarium, then going for a swim in the crystal-clear waters of a natural cenote.

Things to Do

It seems just about everyone has hopped aboard the “eco-green” bandwagon along the Riviera Maya. A number of so-called Eco Parks have sprung up along the coast in the last few years. All seem to be centered upon one or more cenotes.

The largest and most expensive of these eco parks, Xcaret, a quiet cove turned tropical waterside theme park, lies about an hour from Cancún and four miles south of Playa del Carmen on Highway 180. An underground river ride, the park's main attraction, winds through jungle surroundings. Wearing a life-jacket and snorkeling gear, you'll swim through cool water currents that flow through mysterious caves and man-made caletas (inlets). If you've ever wanted to swim with dolphins, this is the place to do it. There's also an aquarium, zoo, botanical garden, butterfly pavilion, mushroom farm, orchid conservatory, a manatee lagoon, wild bird aviary, horseback riding, and an apiary showing how the Maya cultivated bees, plus some archaeological monuments dating from A.D. 1200 to 1550. Your family will also enjoy the reproduction of a Mayan village where costumed dancers perform daily. The hefty daytime admission charge of $59 per person ($41 for children five to twelve; under four free) includes snorkeling and snuba (an alternative to scuba in which you are attached to air pumps aboard a boat) tours. At night, the entrance fee drops to $42 for adults, $29.50 for children. Add $17.50 per person for round-trip transportation from hotels in Playa (998-883-3144, www.xcaret.com).

Grutas Aktun Chen, another of these eco parks, lies about two and half miles past Akumal. Its name means “cave with an underground river inside,” which is what you'll see in this park spanning 988 acres of low-lying jungle. Here, you can take a walking tour of the largest cave, which shows the usual stalagmites and stalactites found in most other limestone caverns. After touring the cave and walking through the jungle filled with tropical plants, you can stop for a drink and a snack at the small restaurant. (Open daily 9 A.M. to 5 P.M. during winter and 9 A.M. to 7 P.M. during summer, 998-892-0662).

Still yet another is Kantun Chi, one mile south of Puerto Aventuras, with freshwater cenotes in which you can swim and snorkel. (Open 9 A.M. to 5 P.M. in winter and 9 A.M. to 6 P.M. in summer, 984-873-0021, www.kantunchi.com.)

For the Kids

Kids love reptiles. And nine miles south of Cancún is Croco Cun, a massive breeding station, where your little ones can marvel at an assortment of more than 300 reptiles displayed in walled ponds. Here, they'll learn how American crocodiles and Central American caymans are raised by taking newly laid eggs and placing them in temperature-controlled rooms. (Open from 8 A.M. to 5 P.M., admission about $4 per person)

Another educational activity for kids is a visit to the Xaman Ha Aviary, part of the Playacar development. Here in a simulated jungle abitat, they'll get to observe over sixty species of tropical birds, including flamingos, toucans, macaws, and parrots, along with butterflies, iguanas, and turtles. Admission is about $15 per adult, plus one child per adult admitted free. (Open 9 A.M. to 5 P.M., Paseo Xaman s/n (sin numero) Fraccionamiento Playacar.)

A Visit to the Past

The Mayan ceremonial city of Tulum, thirty-nine miles south of Cancún, stands as one of the most visited archaeological sites in Mexico, next to Chichén Itzá (outside Merida) and Teotihuacán (outside Mexico City). Though not vast like many other sites, it sits high on a bluff overlooking the turquoise Caribbean, facing the rising sun. Historically rich, it's the most famous site in the area since it's easily accessible as a tour from Cancún. Reaching its peak between A.D. 1000 and 1500, this walled site centers around a plaza that the Maya used for religious rituals. If you climb to the top of El Castillo, the highest and most impressive structure on the site, you get a commanding view of the coastline and sea. A small site by most standards, it gives thousands of vacationers a chance to learn about the history of the Maya. (Open from 7 A.M. to 5 P.M., admission about $3.50.)

If you're a fan of the Indiana Jones movies, then you'll love exploring Coba, the remains of a huge Mayan city set within the jungle inland from the main highway about twenty-five miles west of Tulum and thirty-five miles south of Playa del Carmen. With as many as 50,000 inhabitants, it also served as a ceremonial center from A.D. 300 to 1000. Serving as the regional capital of the Northern Lowland Empire, it features eight stelae (tall carved columns that told stories or kept historic records) in the Cucmuc Mul and nine circular altars in Grupo Macanxoc. The Nohoch Mul, the tallest pyramid in the Yucatán at 138 feet, stands as its centerpiece. All are fine examples of the architectural style of the east coast Maya. (Open from 8 A.M. to 6 P.M., admission about $3.50.)

Although the archaeological site and snorkeling park of Xel-Ha have the same name, they're two entirely different though related places. The first refers to the ruins of a Mayan ocean port, trading center, and religious site where the Maya stored food in case of famine. The second refers to a snorkeling park on the inlet of the same name. Both are thirty miles south of Playa del Carmen. From A.D. 100 to 600, Xel-Ha was the largest town along the coast. Its Palace of the Birds, with murals depicting birds and images of the god Tlaloc, shows ties with the culture of Teotihuacán in central Mexico. A half-mile east of the Palace of the Birds stands Jaguar House, showing a painting of a jaguar, which represents the sacred power of the high priests. This and a building decorated with twisted tiles stand next to a cenote that's part of a vast system of subterranean rivers that lead to the ocean under the site. (Open 8 A.M. to 5 P.M., admission about $2.50.)

Sian Ka'an

If you have the time, you should visit Sian Ka'an, the world's largest biosphere, also along the coast road. This 1.3 million-acre nature reserve, a UNESCO World Heritage Site since 1987, contains tropical forest, wetlands, and marine habitats, including sixty-nine miles of barrier reef. The name “Ziyan Caán,” which the Maya gave to the area that's now the southern part of the state of Quintana Roo, means “Gift of the Sky.” As the third-largest protected area in Mexico, it covers 370,500 acres, containing tropical forests, marshes, mangroves, and a large area of the coast with a barrier reef. It's home to over 1,200 species of animals, including 300 types of birds, as well as jaguars, howler monkeys, and crocodiles.

Amigos de Sian Ka'an, a private nonprofit organization that promotes the conservation of the reserve (984-884-9583), conducts daily tours (except Sundays and Fridays, lunch included) through Mayan canals in open boats for $50 per person. The trip is fascinating and worth every dollar. The number of daily visitors is limited to eighteen to protect the fragile ecosystem. EcoColors Tours also conducts tours of the biosphere by kayak (www.ecotravelmexico.com).