Marino Ballena Parque Nacional (6 A.M.–6 P.M. daily, $6) was created in February 1990 to protect the shoreline of Bahía de Coronado and 4,500 hectares of water surrounding Isla Ballena.

The park extends south for 15 kilometers from Uvita to Punta Piñuela, and about 15 kilometers out to sea. The park harbors within its relatively small area important mangroves and a large coral reef.

Green marine iguanas live on algae in the saltwater pools. They litter the golden-sand beaches like prehistoric jetsam, their bodies angled at 90 degrees to catch the sun’s rays most directly. Once they reach 37°C, they pop down to the sea for a bite to eat.

Olive ridley and hawksbill turtles come ashore May–November to lay their eggs (September and October are the best months to visit). Dolphins frolic offshore. And the bay is the southernmost mating site for the humpback whale, which migrates from Alaska, Baja California, and Hawaii (December–April).

Snorkeling is good close to shore during low tides (although sedimentation resulting from local construction has killed off much of the coral reef) and there are caves worth exploring. Isla Ballena and the rocks known as Las Tres Hermanas (The Three Sisters) are havens for pelicans, frigate birds, and boobies. At the southern end, Playa Ventanas has caves accessible by kayak.

There are ranger stations at Uvita (Bahía), La Colonia, Playa Ballena, and Piñuela. Park headquarters (tel. 506/2786-5392) is at Playa Ballena, but the park is administered by SINAC (tel. 506/2786-7161) in Palmar Norte.

Hotels and Restaurants

All the ranger stations except Bahía permit camping and have showers and toilets; La Colonia has by far the nicest beach and gets packed on weekends.

At La Colonia, the overpriced Hotel Nido del Halcon (tel. 506/2743-8298, www.hotelnidodelhalcon.com, $70 s/d low season, $108 s/d high season) is 400 meters from the beach. It offers 14 modestly furnished air-conditioned rooms with TVs and fridges; plus it has a pool and restaurant.

A far better deal, the nonsmoking Mar y Selva Ecolodge (tel. 506/2786-5670, www.maryselva.com, $85–95 s/d low season, $112–122 s/d high season) has lovely digs in the forested hills inland of Playa Ballena. Ten air-conditioned bungalows feature king-size beds, satellite TV, fans, and heaps of light. There’s a large swimming pool. WiFi is available for a fee.