Centered on the village of La Gamba, the Piedras Blancas rainforest zone was split from Parque Nacional Corcovado  in 1999 and named a national park in its own right. Land within its bounds is still in private ownership, and logging permits issued before 1991 apparently remain valid.
The Austrian government underwrites local efforts to save the forest. A cooperative provides income for local families whose members are employed at Esquinas Rainforest Lodge (which has miles of forest trails) and on fruit farms and a botanical garden; it also has a tepezcuintle breeding program. Guides ($15) can be hired for hiking.
The “Rainforest of the Austrians” also operates La Gamba Biological Station in conjunction with the University of Vienna. There’s no ranger station; the Esquinas Rainforest Lodge is the main resource.
The turnoff from the Pan-American Highway is at Kilometer 37, midway between Piedras Blancas and Río Claro. You can also get there via a very rough dirt road that leads north from Golfito  (4WD required).
Playa San Josecito, about 10 kilometers northwest and a 25-minute boat ride from Golfito, is a wide, lonesome, pebbly brown-sand beach. The jungle sweeps right down to the shore, as it does a few kilometers north at Playa Cativo. The beaches can be accessed by boat, and are popular day trips from Golfito.
Osa Wildlife Sanctuary (tel. 506/8861-1309, www.osawildlife.org , closed May–Nov.), at Playa Cativo, is a nonprofit animal rescue shelter run by Earl and Carol Crews and spanning 304 hectares. You’re welcomed by howler and spider monkeys, scarlet macaws flap and squawk in the treetops, and don’t be surprised if a baby tamandua climbs up your leg and onto your shoulders. Tours are given at 9:30 a.m., 11:30 a.m., and 1:30 p.m. daily. A full-day advance notice is required; children under five are not permitted. Interns are sought. By reservation only.
Casa Orquídeas (tel. 506/8829-1247, 8 A.M.–5 A.M. Sat.–Thurs., $5 pp self-guided, $8 pp guided tour with three-person minimum) has nearly five hectares of private botanical gardens at the northwest end of Playa San Josecito. This labor of love culminates the 20-odd-year efforts of Ron and Trudy MacAllister. Ornamental plants, including 100 species of orchids, attract zillions of birds.
Two-hour guided tours are offered 8:30–11 A.M. Thursday and Sunday. Tour operators throughout Golfo Dulce offer tours to the garden; otherwise take a water-taxi from Golfito or any of the local lodges.
The reclusive stone-and-timber Esquinas Rainforest Lodge (tel. 506/2741-8001, www.esquinaslodge.com , $130 s or $200 d low season, $150 s or $20 d high season, including three meals and taxes) is a great base for exploring the forest. Its five duplex cabins are connected by a covered walkway to the main lodge, which features an open-walled lounge with forest views. Guest rooms have rattan furniture and lively decor, screened glassless windows, and porches with rockers and hammocks. Facilities include a bar, gift shop, library, and thatched dining room plus naturally filtered swimming pool. Excursions are offered. Simple bunks at La Gamba Biological Station (c/o Esquinas Rainforest Lodge, $8 pp) accommodate eight people in a small, self-contained farmhouse.
Anglers are catered to at Golfito Sailfish Rancho (U.S. tel. 813/249-9908 or 800/521-0072, www.worldwideangling.com/node/67 ), at Punta Encantado. This modern sportfishing lodge offers 10 spacious, pleasingly decorated rooms with ceiling fans, two double beds, safe, and walk-in showers with hot water. Most folks come in to fish on multiday packages; contact the resort for rates.
The Swiss-run Golfo Dulce Lodge (tel. 506/8821-5398, www.golfodulcelodge.com , from $105–115 s or $170–190 d low season, from $315–345 s or $510–570 d high season, including transfers, meals, and taxes), surrounded by 275 hectares of forest at Playa San Josecito, has five handsome wooden bungalows plus a brick cabin with bamboo furnishings, large veranda with hammocks and rockers, and tiled bathrooms. There are also three rooms with verandas. There’s a small swimming pool and a rancho-style restaurant and bar. Sea kayaking, horseback riding, hikes, and excursions are offered. Electricity is supplied by a Pelton wheel, water is recycled, and sewage is treated in septic tanks.
Fronted by a beach and coral reef (good for snorkeling) and backed by a mountain with trails leading into a 77-hectare private reserve (a former cacao plantation that is being reforested), the splendid Playa Nicuesa Rainforest Lodge (tel. 506/2222-0704, in North America tel. 866/504-8116, www.nicuesalodge.com , $195–230 s or $320–540 d low season, $225–260 s or $380–630 d high season) is a perfect base for adventures. It was added to the Small Distinctive Hotels of Costa Rica group in 2010. Crafted entirely of multi-hued hardwoods, the two-story open-atrium ecolodge is a stunner. Four hexagonal cabins and a four-room guesthouse spread throughout the forested grounds all feature a quasi-Japanese motif, canopied beds, ceiling fans in open-beam roofs, and full-length wraparound louvered doors, plus open bathrooms with outdoor showers. The open-air upstairs lounge–cum–dining room looks over the lush grounds, candlelit at night; the lodge grows most of its own organic produce. It has family programs, and yoga is offered on the beachfront deck. River otters and caimans frequent the lagoon accessed by kayaks, and animals have been known to pay visits into the cabins. How exciting: “An ocelot slept here!” Closed October–mid-November.
Finca Saladero (tel. 506/8761-0425, www.fincasaladero.com , $10 s/d camping, $95 s/d tree house, $135 beach house) aims to compete. It permits camping on manicured lawns and offers a fully screened tree house (reached by a long staircase) and a delightfully airy and nicely decorated two-story beach house. It also has its own rainforest reserve, and rents kayaks and snorkeling gear.
Agua Dulce Lodge & Resort (tel. 506/2723-0766, www.aguadulcelodge.com , contact the lodge for rates), at Playa Preciosa, has 21 air-conditioned two-bedroom cabins and specializes in sportfishing packages.