Light pollution from Tamarindo is making life harder for leatherback turtles. The town's lights disorient the tiny hatchlings, sending them toward the luminescence instead of out to sea, where they are safer from predators.

"These large-scale tourism projects have big consequences for the environment," said Fabian Pacheco, of the Costa Rican Federation for the Conservation of Nature.

Surf's up

The issue is a familiar one in developing countries as they weigh the benefits of tourist dollars that come with high-rise hotels against the loss of greenery when virgin land is paved over.

Tourism is Costa Rica's top foreign exchange earner.

Property developers point to the big contribution the construction sector makes to the economy, accounting for 5 percent of gross domestic product and growing by 16 percent last year.

The tourist boom has also created jobs in a poor region.

"It's been good for the locals. Most of them are happy to have good, decent jobs," said Denise Shante, 51, a Canadian property broker who sells apartments priced up to $2.5 million.

As Costa Rica attracts more mainstream tourism, neighboring Panama is aggressively promoting its own eco-tourism credentials.

The breakneck development has the government and even the tourism industry worried.

When rains overflowed septic tanks in Tamarindo, tons of raw sewage flowed into the ocean and the resort lost its "blue flag" issued by Costa Rica's water utility to indicate healthy ocean water conditions.