As I barrel down the highway from Cancún, it's clear that vast tracts of mangrove wetlands have been bulldozed to make way for all-inclusive resorts. In the past decade, Playa del Carmen has exploded, real estate prices have skyrocketed, and hotel rooms have increased from 3,500 to 30,000. In five years there will be 50,000. "Until recently, most of the money stayed in Cancún," says Felipe Alvarado, assistant manager of KaiLuum Cito, a small, idyllic ecotourism resort some 200 miles from Cancún, near Majahual. "The government is trying to move that money south."

The money is moving so fast, in fact, that some small-scale resorts have been pushed out of business. KaiLuum Cito is owned by Clayton Ball, an American whose family pioneered ecotourism in the Yucatán in 1976 with the original KaiLuum, an elegant tent camp on the beach 43 miles from Cancún that was forced to close last year. "We were leasing our land from an adjacent resort, and they got offered $14 million for the property," Ball tells me. "They held out for a while, but finally the price went so high they sold it." Anticipating that development will continue moving southward, Ball not only opened KaiLuum Cito; he also bought property even farther down the coast and is prepping it for KaiLuum's next incarnation.

There have been other troubles, too. By paving the mangroves, the big hotels destroyed natural hurricane buffers and habitat for a vast range of wildlife, from anteaters and iguanas to migratory songbirds. Business owners complained that the all-inclusive resorts attracted visitors who, having paid for their food and drinks up front, were too cheap to sample the locally owned bars and restaurants. Boomtowns like Playa del Carmen were growing so fast, sewage systems and treatment plants couldn't keep up, and the groundwater was becoming polluted. Gringolandia, it seemed, was sprawling out of control.

And then, surprisingly, state and local officials rose up against the Cancúnization of the Riviera Maya. Fearful of losing the natural "green gold" landscape that attracts more adventurous travelers, the state of Quintana Roo in 1994 passed strict zoning laws that limit the height of hotels and require tough new environmental protocols. Perhaps even more startling, the state has actually enforced them. Four years ago, when Fairmont Hotels proposed a new megaresort called Mayakoba, north of Playa del Carmen, state officials asked the corporation to rework its original design to meet with the new environmental standards; Fairmont readily complied.

"Instead of one hotel next to another, we want the resorts to be surrounded by jungle," says Dario Flota, executive director of the Riviera Maya Tourism Board. "We've got to keep the ecological conditions strong, because that's what makes the Riviera Maya attractive."