What to Expect: The cenotes have moderate water temperatures of about 77F and mind-boggling visibility of 200 feet plus. Out on the Caribbean reefs expect an average water temperature of 82F and visibility of 80 to 200 feet.
When to Go: Year-round. November through May is the dry season.
What to Wear: Cenotes generally require full-length 5 mm wetsuits with a hood. For shallow dives on the reefs a skin works. For deeper dives, wear a 1.5 mm three-quarter suit.
Getting There: Many visitors arrive at the international airport in Cancún. There are direct flights to Cancún from many U.S. cities. There are also many direct flights to Cozumel.
Currency: Mexican peso.
Taxes: The tax on hotel rooms in coastal Mexico ranges from 15 to 17 percent.
Electricity: 120 V, 60 cycles.
Dialing In: From the United States callers must dial 011, then 52 (Mexicos country code) and then one of two area codes before dialing the seven-digit local number. The area code for Puerto Morelos is 998; for Playa del Carmen, Tulúm and the areas between, it's 984. To reach another country from Mexico dial 00, the country's international code and then the number.
Time Zone: UTC/GMT 6 hours.
Required Documents: A passport or birth certificate with a photo I.D. All visitors to Mexico are given a tourist card on arrival; this needs to be presented at departure.
Key Gift: Maya wood carving.
Don't Forget: To leave your resort. Many resorts tempt with sheer comfort don't fall into that trap. There's much here to explore.
The Vibe: The Siesta (for now) Mexican Coast.
Topside: All-inclusive resorts, small one-of-a-kind properties run by expats, sea breezes unencumbered by buildings, sleepy towns with central plazas and small cafes, fishermen unloading their catch at piers, small signs pointing down gravel beach roads, and some inevitable congestion from rapid growth.
Find your way to Playa del Carmen, a culinary hotbed seasoned by European and Mexican chefs. Visit the Tres Rios Nature Reserve. Tour a Maya village (arrangements can be made in Playa del Carmen). See the Museo CEDAM in Puerto Aventuras, which covers the history both of Mexican scuba diving and of the Riviera Maya wrecks. Visit the Maya ruins at Tulum, the Caribbean coast's greatest historical attraction. Sit in San Miguel's central plaza on Sunday evening and listen to bands playing everything from salsa to mambo to military marches. Try fly-fishing in solitude on the empty reefs of Costa Maya. Visit the pyramids of Coba (25 miles west of Tulum). Find a (shaded) hammock. Contemplate the blue sky by day. Return to consider the floods of stars.