Ostional, one of the four area beaches, is itself a wildlife refuge, as its black, volcanic sand is a breeding ground every July until early December for hundreds of thousands of Olive Ridley sea turtles. They climb onto the sand to lay their eggs, and a fraction emerge approximately 60 days later as newborn turtles. The ocean waters are a gathering spot for humpback whales, which migrate through the region during the same months. And the nearby Reserva Biológica Nosara boasts at least 270 types of birds, such as orange-chinned parakeets, cinnamon hummingbirds, long-tailed manakins and black hawks.

“There is a freshness in Nosara that is pretty compelling,” said Mr. Johnson, in torn jeans shorts and a patterned, partly unbuttoned, short-sleeved shirt during a recent visit. “It’s kind of an analog to a little ski town, like the early days of Telluride.”

There was one other critical ingredient that Mr. Johnson found here: Susan Short, a naturalist, filmmaker and also a surfer, whom he met on one of his early visits to Nosara and who is now his wife and partner in their business endeavors.

The couple have gone on something of a buying spree in town, purchasing two small hotels; two unfinished condo developments; and even the local weekly newspaper. They are determined to prevent large-scale, resort tourism from taking hold, and have enough available capital to actually stop it.

Image One of the hundreds of thousands of Olive Ridley sea turtles that breed on Playa Ostional from July to early December. Credit... Toh Gouttenoire for The New York Times

The centerpiece of this effort, at least so far, is the 24-room Harmony Hotel, which has the aura of a Lana Del Rey music video — with its 1950s-era tropical décor, its super-attractive, super-fit clientele, its juice bar and healing center with classes like Yin & Yoga Nidra.

The Harmony is not a place that pampers its guests, despite the premium price: The rooms are relatively small and hardly luxurious (and lack televisions), and room service is not offered. (Rates range from $210 for a basic room in low season to $990 a night for a two-bedroom bungalow over the Christmas holiday.) Mr. Johnson is proud of the fact that it serves no sugary sodas or junk food. Even the minibar is stocked with treats like a homemade granola bar and artisanal chocolate.