On a quiet night in February, when winter temperatures plummeted below zero in North America, leatherback sea turtles the size of golf carts lumbered onto this tropical beach to lay their eggs.
Yet just a sandy stroll away, in the booming surf town of Tamarindo, runaway tourism development is turning the sea into an open sewer.
Water quality tests conducted by the country's Water and Sewer Institute (AyA) over the past year found fecal contamination far above levels considered safe by the United States Environmental Protection Agency (EPA).
Such contradictions are now a part of everyday life here, as this ecohaven the size of West Virginia struggles to deal with a tourism and development surge three times the world average.
"Welcome to the Costa Rica the promoters don't want you to hear about," says Gadi Amit, tireless leader of a local activist group called the Guanacaste Brotherhood Association.
In the past decade, construction of hotels, second homes, and condominiums has surged in coastal regions, taking advantage of a vacuum in planning and enforcement. The total land area that has been developed grew 600 percent in that time, according to a government report.
As a result, the biodiversity that has long lured visitors is disappearing, say scientists. Monkey and turtle populations are plummeting, and infrastructure is strained to a near breaking point.
Now a streak of alarming environmental calamities has the government caught in a tug of war between investors and environmentalists wanting to protect natural resources.
"This is a free-for-all," says Mr. Amit, "and it's coming at the expense of local communities and the environment. If something isn't done soon ... there will be no reason left for tourists to come here."
Costa Rica's highly regarded, nonpartisan State of the Nation report aired the country's dirty laundry last November, alarming both the press and the public.
Statistics revealed that 97 percent of Costa Rica's sewage flows untreated into rivers, streams, or the ocean, and that more than 300,000 tons of garbage was left uncollected on streets in 2006. And a flurry of illegal well-drilling is running aquifers dry, ironic in a country where as much as 20 feet of rain falls annually.
Despite the chaos, less than a quarter of coastal towns have zoning plans to balance tourism development with natural resources and government services such as sewage treatment and public water supply.
The report's authors concluded that the government "lacked a clear political commitment" to reduce environmental impact, and that investors simply "lacked interest."
Forcing discussion of the issues has become the mantra of the country's burgeoning environmental movement. Community activists are organizing, filing lawsuits, calling for development restrictions, and insisting on their constitutional right to a "healthy environment."
Last year, a rash of alarming reports validated their fears.
Monkey populations, symbols of the rain forest and a charismatic tourist attraction, declined an estimated 50 percent in little more than a decade, according to a recent report by a team of wildlife scientists.
In the northwestern province of Guanacaste, luxury hotels and condominiums were once unheard of. But along those booming shores, recently anointed as the Gold Coast, such accommodations are now the norm.
These sprawling developments, with their well-manicured lawns and golf courses, produce a soupy, nutrient-rich runoff that feeds caulerpa sertularioides, an aggressive species of algae that is smothering coral reefs in the Gulf of Papagayo.
"It's an ecological disaster," says marine biologist Cindy Fernández, who spent years cataloging the damage.
Sea turtles, another tourist favorite, are also threatened. Populations of the critically endangered Pacific leatherback have plummeted 97 percent in 20 years, say scientists. While the threats leatherbacks face range from fishing to global warming, many scientists believe development, particularly along Costa Rica's nesting beaches, may be the last straw.
The government has been slow to rally to the turtles' defense.
"Everyone is fed up," says Frank Paladino, a biologist and vice president of The Leatherback Trust, a nonprofit based in New Jersey that raised millions of dollars to protect the turtles. The group, frustrated and feeling pressure from donors, recently broke a long-standing fundraising agreement with the country's environment ministry. "We can't keep waiting for the Costa Rican government to do the right thing," Dr. Paladino says.
The solution, agree most activists and scientists, is better planning and stricter environmental safeguards.
"We're not asking to end all development," says Jorge Lobo, a University of Costa Rica professor. "What we need is to take a break, so that our coastal municipalities can catch their breath, set zoning plans and laws in place, then resume, but at a more sustainable pace." Professor Lobo has led the charge for development moratoriums in sensitive areas of the Osa Peninsula, a region scientists say boasts 2.5 percent of the world's biodiversity.
A torrent of revealing local and international press coverage may pressure the country to turn the corner.
Travel guides, including the "Lonely Planet" series, have led the way. The most recent edition warns: "If anyone reading this thinks that Costa Rica is a virtual eco-paradise where environmental conservation always takes precedence over capitalist gains ..., educate yourself...."
"Ecotourism is a media phenomenon," Mr. Kaye says. "The people that are really willing to sacrifice comfort for sustainability are few. That would need to change."
Setbacks aside, promoters such as Kaye, and even many detractors, acknowledge that Costa Rica remains decades ahead of its neighbors. More than 26 percent of its national territory is under protected status, 80 percent of its energy is produced from renewable resources such as wind and hydropower, and the country is growing more trees than it cuts down – an anomaly in widely poor Central America.
Costa Rica's natural resources are equally impressive, with its 11,450 species of plants, 67,000 species of insects, 850 species of birds, and the highest density of plants, animals, and ecosystems of any country in the Americas.
Lately, the government, sensing the urgency of the situation, seems increasingly willing to listen.
In January, the Health Ministry closed the Occidental Allegro Papagayo, one of the country's largest all-inclusive resorts, when inspectors discovered pipes pumping sewage into a nearby estuary.
The state-run Water and Sewer Institute stepped up next, revoking "Ecological Blue Flags" from seven beaches, including those fronting the popular tourist towns of Dominical and Tamarindo on the Pacific, and Puerto Viejo, on the Caribbean, citing fecal contamination in ocean waters.
And on April 9, the Costa Rican administration issued a temporary decree restricting building height and density along the northwest Pacific coast, the country's fastest-developing region, and coincidentally, one entirely without zoning plans.
"Things will likely get worse before they can get better. Remember, in the United States, rivers were catching on fire 30 years ago," says ecoindustry leader Kaye. "We are making progress."