VERY SHORTLY, anyone interested in world tourism development will be aware of Cancun. Its green, sunblessed shores and warm, clear waters will be the scene of a major new tourist center: The Mexican Caribbean. Cancun's dramatic development will demonstrate how government planning and funding can be combined with international banking aid to speed Mexico's growth. In addition, Cancun will offer attractive investment and vacation opportunities to many people around the world."

From a government brochure, June 1973

The Maya called this place "Pot of Gold," and they couldn't have picked a better name. Mexican tourism has apparently struck rick paydirt. And in view of our good neighbor's serious need for foreign exchange earned by its "industry without chimneys," that's good news.

This computer-selected, most heavily touted and most expensive of all Mexican resorts has just played its third winter season to a packed, well-banned and mostly appreciative house. Cancun's future success (regardless of that the jet set does) seems assured - unless too many people jam it and spoil it.

Mayan kings may have vacationed on this 14-mile-long island just off the Yucatan peninsula more than 1,000 years ago, as the ads claim, but they certainly never left beer cans on their virgin beach. That virtually has since been gently compromised in order to welcome pale gringos, and unfortunately the cans are now there - only a few, admittedly, and most of the debris dropped thoughtlessly by growing numbers of foreign and Mexican tourists is swiftly removed by conscientious cleanup crews.

However, the trash seems to be symbolic of one of tourism's (and the world's) major problems: People Pollution.

Happily that threat is a long way off here, despite the high Mexican birth-rate that remains a deep concern of some politicians seeking the elusive solution to their country's growing poverty, lack of jobs and inadequate arable land.

After all, Cancun is just about as far as you can get from one of the world's most crowded capitals, Mexico City, and still remain on Mexican soil. For many reasons, including isolated location and lack of industries, it's not likely to become another magnet for an uncontrolled influx of permanent residents.

And as for tourism planning, Cancun is not being built by amateurs.

Regrettably, though. I find the resort almost completely without character, a fact that should be neither unexpected nor difficult to understand considering the artificial method of creation. It will take years before the people of Cancun can develop roots, before the rich Mexican/Yucatecan culture that undeniably exists in and around the state of Quintana Roo can flower here, and before the new city can develop the colorful, inviting "ambiente tipico" found in so many other Mexican areas.

But let's not quibble too much. Right now, I'd rate those miles of unencumbered white beaches (whose soft powdery sand, composed of lime-coated particles and small pieces of shell, cannot burn tender bare feet because it does not hold the sun's heat) as one of the very finest strands in the Caribbean. Perhaps THE finest. It certainly beats my earlier favorite, the beautiful 7-Mile Beach on Grand Cayman island.

The annual mean temperature of around 80 degrees, combined with cooling tradewinds that fan the water's edge, assure pleasant sunbathing, though the deceptive breeze can mask the strong tropical Yucatecan sun and cause the unwary to rapidly suffer a serious burn. There are more than 240 days of sunshine a year, according to official figures. The only thing resembling a "rainy season" occurs in September and October.

The close proximity to Miami - 518 miles or 1 hour, 15 minutes by jet - is another factor in Cancun's favor and another reason (besides Cuba's recent bid for a resumption of U.S. tourism) why other Caribbean islands are worrying even more about the increasing competition for the U.S. travel dollar. Cancun is closer to Los Angeles than Miami.

Some deep Caribbean areas may have warmer waters (cool currents occasionally push onto the Yucatan coast in winter), but Mexicans have none of the color consciousness or identity problems sometimes found on other islands that have suffered traumas from their colonial past, their recent struggles for self-determination and other factors including economic handicaps.

Indeed, when the Cancun project was originally announced in June 1973, a factsheet made direct reference to "unrest and social problems at other Caribbean island resorts" and stated that "Americans have been increasingly reluctant to go to vacation spots marred by domestic turmoil." The Caribbean, it should be pointed out, has since made great strides in improving its tourism product, and some islands have reported an excellent season this past winter.

Ironically, Mexico itself in recent years suddendly found it was losing millions of dollars in tourism revenues as a result of internal problems that arose under former President Echeverria. Cancun, however, far removed from the "trouble spots" and basking the demand for its shiny new "in" status generated by heavy publicity, did not suffer much, if at all. Now, with Mexico enjoying a tourism boom, Cancun's hotels continue to experience a high occupancy level, due in part to back-to-back group air charters - 53 flights are scheduled just from May through December of this year.

As Americans have come to expect, the friendly Mexican people, with a firm grasp on their national and individual identities despite centuries of turmoil, still greet the visitor with genuine warmth rather than with the out-stretched palms too often found in many parts of the world. And for the most part, they manage to transmit the feeling of being at piece with themselves even when not satisfied with the hard economic lot that many have befallen them in a country whose "revolution" ostensibly continues after more than 50 years.

They do not feel stigmatized by performing tasks such as waiting on tables, or cleaning rooms, or maintenance chores, which means that dollar-spending guests at resort hotels do not face antagonistic or unpleasant attitudes. Signs of poverty, which can be easily viewed in many parts of Mexcio, are not seen in gleaming Cancun. In the long run, of course, the future of tourism depends, in large measure, upon whether President Lopez Portillo can improve economic conditions for his country's masses and retain stability.

Years before the first bulldozer - much less the first modern-day visitor - appeared on Cancun, the Mexican government decided that, in order to improve its balance of payments, it would launch "a major program to find and develop new tourist resorts . . . aimed at giving Mexico a larger share of the international tourism market while aiding in the growth of lower income zones of the country."

First, statistics on Caribbean tourism were gathered and fed into a computer. Then the country was canvassed in search of suitable sites in underdeveloped areas. Additional figures on beaches, weather, available manpower, natural resources, distances from major U.S. cities and other criteria were added to the computer record. Finally, Cancun and another site (Ixtapa on the Pacific Coast, also now open) were selected as "ideal." In the case of Cancun, the task was to build from scratch a resort and a city with housing and essential municpal facilities for the "resident labor force . . . recruited from the areas around Cancun" so "the surrounding population will not only enjoy the fruits of Cancun's new tourist industry but will taste of her municipal prosperity as well."

Responsible for the tourism infrastructure (essential facilities such as roads, power, water, sewage treatment, jetport) was INFRATUR, now FONATUR, the developing agency which is a government trust administered by the Bank of Mexico. Mexico's initial investment was $48 million, which includes a credit of approximately $21.5 million from the Inter-American Development Bank. Private capital, both Mexican and foreign, is primarily responsible for development of hotels, convention and commercial facilities and other tourist services. To date, more than $200 million has been "committed and invested by FONATUR plus the hotel."

The small but modern airport, which alone has cost $10 million so far and can handle 747 jumbo jets, is one example of the kind of benefits. Mexicans see in their "integral master plan." The airport was built at one end of the island, and the flight pattern is designed so that no planes need pollute the resort area with jet noise on takeoff or landing.

Mexico claims that, unlike "other major resorts," Cancun will not suffer from "haphazard development" but instead will suit "the sophisticated and discriminating traveler." And as a Mexican official stated at the outset:

"We believe that Cancun will be rated as one of the world's most exciting and beautiful resorts. We will provide our visitors with excellent food, pure and clear drinking water, and first-class service by friendly people who are direct descendants of the Mayan civilization. The breathtaking view of the unrestricted beachfront rivals any other anywhere in the world."

So let's further evaluate the resort at this stage of development.

I flew from Miami on Mexicana Airlines, which offers 727 service to Cancun five years a week with a 5:30 p.m. takeoff. The excursion fare from Washington's National Airport was $258.30 round trip. But because of the early evening departure you spend an entire day in transit en route, and must leave your Cancun hotel at midday for the return flight. Still, there's no quicker way to escape from a rigorous Washington winter or the summer blahs.

The beauty of the narrow (one-quarter mile) island is not visible at dusk, but upon leaving Cancun in early afternoon the sun glints on the white, sandy L-shaped strip far below the plane and reveals the lovely shades of aquamarine that vary according to the coral and the sea's depth.

Customs, in line with Mexico's policy of simplifying and facilitating tourist entry, did not open my suitcase. After I was swiftly checked by immigration, my bag was stamped and I was free to enter a waiting limo-van ($2 - only cabs are available when going from hotel to airport at a flat $5 rate). The 12-mile, 40-minute ride to Hotel El Presidente took me past the heart of the Cancun City business district; then, heading out from the mainland along the narrowing strip leading to the Zona Turistica, we crossed a new bridge, sped past more hotels, an 18-hole golf course designed by Robert Trent Jones Inc., and stopped at the adjacent El Presidente.

On one side of the snake-like highway running the length of the tourist zone is a salt-water lagoon, and on the other lies the Bay of Women. Hotels like Playa Blanca, Bojorquez, Villas Tacul, Maya Caribe and El Presidente are located on that strip facing the bay, where there is almost no wave action due to the cove. The gentle water, combined with a shallow initial beach area and an absence of any sudden drop off, which occurs farther out from shore, means excellent swimming conditions for the novice and safety for small children.

By contrast, those who like strong waves with Hawaiian overtones may wish to book a room at hotels like the Camino Real, Aristos, Cancun Caribe or Garza Blanca, which are situated on the "foot" or the "L" and thus face the open Caribbean. Though lifeguards are provided in many cases, I do not recommend those beaches for children, nonswimmers or poor swimmers, because - contrary to statements in the original publicity release - there are undertows, as warning signs on the Camino Real and Cancun Caribe beaches clearly acknowledge.

Until recently, the island had no permanent population and only a few fishermen intruded. Now there are 25 hotels, with 2,164 rooms (which includes 300 rooms at Club Med's very successful, secluded beachfront pad at Punta Nizuc), and about 20,000 residents in Cancun City. The master plan calls for more than 5,000 rooms when the second phase ends in 1960. Marriott is scheduled to build a major resort. In 1976, Cancun hosted 180,450 guests. In the 1980s it expects three quarters of a million visitors a year, with 10,000 rooms and a million tourists by 1992.

I am not sure I'll want to be among that many tourists here, despite the expressed concern for ecology (both floraand fauna), tight controls on hotel size, provision for green zones and open areas, and prohibitions against walling off the sea with beach-front construction (a la Miami Beach). Incidentally, there are no "private" beaches in Mexico and the public has access to all beachfront. Natives of Cancun, regardless of economic status, can be seen relaxing with their families, usually at convenient designated public beach areas. (Along with the "working class" day-visitors, of course, are many well-to-do middle and upper-class Mexican tourists who have apparently survived two devaluations and can afford to stay at the new hotels built primarily, but certainly not exclusively, for gringos. Mexico's president enjoys a vacation break here).

I have been spoiled by uncrowded beaches; the peaceful sounds of water and birds uncontaminated by loud voices and blaring transistor radios (the latter are not yet a problem at Cancun but they should be banned from beach now); a gentle pace, and the opportunity for a genuine cross-cultural experience. No matter how much sincere care is taken by the officials of FONATUR, wholesale tourism involving the continuous large-scale airlift, care and feeding of hundreds of thousands of visitors remains a foreign, unnatural intrusion.

Mexico will gain dollars, but those who seek to avoid being lumped with mass tourism will lose a precious quality.

Yet, to be fair, group tourism and its concommitants, charter flights and packaged vacations, have become absolutely essential due to the rising cost of travel. Indeed, I would have to strongly advise the reader to consider a 7-day OTC (one-stop tour charter) to Cancun, if one can be found leaving from this area when you want to go, because there are certainly savings to be had on the total cost of the trip, compared to individual travel. (With small children, however, there may be insufficient savings for a family, so it's wise to compare the package with the cheapest air fare and hotel rates.)

Mexico is, at the moment, highly competitive pricewise with the Caribbean, due to devaluation of the peso. And even though Mexican travelers say Cancun is now the most expensive resort in the country for them, an American receives between 20 and 23 pesos for each dollar spent. Which is why a single at the big, tour-besieged El Presidente, for example, was only $33.60 (without meals), and a double was around $38, plus 4-per-cent tax, during this winter's high season - a drop of around 10 per cent from last year's rate (and they had projected a 20-per-cent increase before devaluation hit them). Rates at the somewhat plushier Camino Real were slightly higher. There are also villas and condominiums, some for sale at extravagant prices.

Yet for the younger and/or fancy-free types who may not mind settling for a small room in an in-town hotel on a busy street - if it costs only $10 a night - a rented motorbike or a 5-peso bus fare (about 20 cents) will take them to the ritzy hotel beaches in a matter of minutes.

I do not think Mexico will hold the price line next year - nor do I think it should be expected to do so - the cost of food and services continues to rise worldwise. But unless Cancun can keep hotel and restaurant prices from rising too rapidly and too high, a major advantage in this most competitive field will be lost.

What about food, water, health conditions and activities?

Health conditions are excellent, so if you become a victim of Moctezuma's Revenge or the Aztec Two-Step the reasons may be far different than you suspect. While it is true that gastroin-testinal ailments affect a large percentage of visitors to Mexcio (despite efforts to soft pedal it), if you fllow the usual strictures in Cancun (avoid eating uncooked vegetables, leafy salads, fruit that cannot be peeled, and too much unaccustomed but delicious Mexican fruit), you should greatly increase your chances of avoiding a few days of generally mild illness.

I was not sick, but I am furious because of what seems to me to be an incomprensible failure by authorities to clarify the drinking water situation. The confusion caused me to waste time searching for bottled mineral water (since I could not afford probelms in my few days on assignment) and spend additional money, because I did not like the sloppy way bottled ("electropura") water was provided or the myriad explanations I heard. According to Mexican engineering officials, as quoted by the Cancun Information Bureau in New York, the newly built water system (drawing upon the underground water table) in Cancun involves a standard chlorination process and the tap water is thus perfectly safe to drink. (I did not learn this in time.)

But because the Mexicans decided that American tourists "won't believe" it's safe, they have caused hotels to provide bottles of "purified" water in rooms (in my hotel the bottles were unsealed and often unlabeled) and to serve in restaurants what is described as "purified" water. Waiters will tell you the tap water is unsafe (because that's what they think you want to hear?), but I was told that the kitchen of the government-owned El Presidente uses water from the tap - with a filter attached (there are no filters on the room taps, of course).

One young hotel worker told me his family had to buy "electropura" because the water system did not yet serve Cancun City, but Mexican authorities said it already does. (Using a "biological" system, all wastes are carried by underground pipes from the hotels to a treatment plant in Cancun City, and the effluent is used only for irrigation purposes, officials said.)

My suggestion is that signs be immediately posted in all rooms telling guests that the water is safe to drink. If it is. And if visitors insist upon ignoring the simple precautions about certain foods, swimming in dirty hotel pools (I saw some), and (as one tour guide told me disgustedly) trying to drink up all the Mexican beer while frying for hours in the tropical sun, they shouldn't blame the drinking water when they get sick.

The hotel food is generally good but definitely not exceptional. Quality is uneven and varies from dish to dish. Try the fresh fish. One of the best hotel meals is the buffet breakfast at El Presidente - all you can eat of papaya, melon, pineapple, juice, eggs, cereal, grits, meat, pancakes, beans, pastry for 55 pesos. But the two finest meals I had were at the Hotel Mayaland at Chichen Itza, and at a native restaurant at Akumal, a delightful low-keyed beach area about an hour and a quarter from Cancun on the road to the Mayan ruins at Tulum.

What else to do? No bargains in shopping, but certainly there are some native crafts and foreign imports. Mexican silver is not cheap but the quality is excellent. You can go boating, fishing, or snorkeling at nearby Isla Mujeres. You can also look for the descendants of the Maya; not many of them work as waiters because they are still studying English and Spanish and undergoing training. They have been employed mostly in construction and landscaping.

I saw not a single crawling insect in Cancun, by the way. If the mosquitoes have really been vanquished, that's an incredible triumph. But if you take a sidetrip to the ruins at Chichen Itza, and stay overnight at one of the hotels at the edge of the "jungle," don't go poking around the bushes - they've got fat tarantulas and poisonous snakes.