Across the Gulf of Nicoya on the mainland, near Manuel Antonio National Park, adventurers can kick in their endorphins in countless ways: Equus Stables takes riders galloping and cantering along the sprawling white sands; Iguana Tours leads kayakers through mangrove swamps and estuaries to some of the park's emerald islets; the experienced guides of Blue Fin Sport Fishing let anglers pose for snapshots with their prize marlin, tuna, or sailfish before detaching the hook and setting their catch free.
Dozens of hotels around Manuel Antonio cater to every type of traveler (European, gay, vegetarian) on every type of budget, but the top spots are those with secluded suites on the ridge above the beach. The adults-only Makanda by the Sea, a collection of 11 freestanding villas, is encircled by a rain forest. Apart from the private cove and Japanese-inspired accommodations—notice the rock garden?—Makanda has that other luxury rarely found in Costa Rica: good food (fresh-fish tacos, blackened shrimp). Breakfast is presented on your private veranda; during lunch at the Sunspot Restaurant, you can spy toucans, two- and three-toed sloths, and spider monkeys.
Nearby, the spare wood-and-stucco cabanas at Tulemar, also on the ridge, are furnished with teak armoires, fully equipped kitchens, and jungle or ocean views from all sides of the octagonal structures. The seven just-opened deluxe bungalows emphasize space—1,400 square feet inside, 400 outside—and each has two bedrooms, a rainfall shower, a private garden or balcony, and panoramic vistas.
Time: Five days. In southern Costa Rica, the remote Osa Peninsula is one of the most biologically dense tropical regions on earth. Scarlet macaws do flybys past the lodges, howler monkeys swing from the forest canopy, and whales migrate along the coast. Basically, if it lives and breathes in Costa Rica—caiman, iguana, sloth, jaguar—it probably resides in the nature preserves, public and private, that blanket this peninsula. Some of the world's first ecolodges were built in the undeveloped jungles of Drake Bay, Golfito, and Corcovado National Park; they are still models of sustainable tourism today.
When they opened Lapa Rios in 1993, Americans Karen and John Lewis pioneered the practice of ecotourism in Costa Rica. The 16-room hardwood-and-thatch resort on 1,000 protected acres of jungle and Pacific oceanfront continues to win conservation awards. Visitors often plan their Costa Rican vacations around availability at Lapa Rios, whose friendly service and surprisingly creative meals—not to mention alfresco showers, private decks, and abundant wildlife right outside your screen door—make up for the rickety prop plane (and the airsickness) that gets you there. Just be sure to take a low-numbered room: the higher they get, the farther the trek up and down the steep incline on which the villas are built.
The nearby Bosque del Cabo gets less attention but deserves equally high praise. Set at the end of a mile-long drive in another 500-acre preserve, its 13 bungalows have rustic cane beds, garden showers, and private sunbathing decks with hammocks. The expert forest guides on staff can take groups hiking, horseback riding, or flying over the trees on the hotel's zip lines.
The newest biosensitive resort on the peninsula is the Playa Nicuesa Rainforest Lodge in 100,000-acre Corcovado National Park, across the Golfo Dulce from Golfito. Everything here is recycled: the four cabins and a four-bedroom house are made from farmed trees; covering the roofs are tiles made from bags that once used to protect banana stalks; and solar energy provides the electricity. Accessible only by boat, the hotel keeps guests busy with kayaking, fishing, snorkeling, windsurfing, and, of course, naturalist-guided hikes.
The only other place to stay inside the park is Corcovado Lodge Tent Camp. Guests fly into Carate by prop plane, drive two hours to the shore, and then walk along the beach for 45 minutes to reach 20 steel-framed tents that guarantee utter privacy (from humans, anyway). A little pleading with the guides (and a lot of Valium for yourself) gets you and your partner harnessed into a bed built into a platform 100 feet above the jungle floor, where the two of you can spend a night under the stars.
Time: Three to four days. If no one told you otherwise, you could easily mistake Tortuguero National Park, on Costa Rica's east coast, for the Amazon. This dense forest was carved out by a series of rivers and canals dug to ease the transport of timber before the area became protected in 1970. Easier to reach (and cheaper to stay in) than that other basin in South America, Tortuguero has turbulent Caribbean beaches that give safe haven to four turtle species, including the Atlantic green, during the summer nesting season. It's also the stamping ground of tapirs, caimans, anteaters, coatis, and the electric-blue morpho butterfly.
The hotels along Tortuguero's lagoon specialize in guided cruises down the area's waterways by canoe or small motorboat. You can get a free nature tour if you approach the hotels by water: your craft will be greeted with the squawks and screeches of countless species of birds and monkeys. Pachira Lodge, a rustic resort with almond-wood cabins and a pool shaped like a turtle, attracts a mostly European clientele, which gives it a relaxed, rather festive vibe. Tortuga Lodge, whose 24 rooms are distributed among five bungalows, has a lovely river-rock pool and excellent service: the general manager calls guests by name, and the chef can prepare basic dishes that aren't on the simple set menu. Both Pachira and Tortuga have plenty of kayaks and motorboats for canal cruising and are absolutely silent at night, save for the rhythmic rush of the Caribbean across the peninsula on the other side of the lagoon.