Private reserves, colourful casitas and boutique retreats

Kura Design Villas, Uvita de Osa

This boutique retreat opened on a mountain ridge overlooking the whale-tale-shaped sandbar of Uvita de Osa this year. It offers six luxury villas with views across the Pacific Ocean. Each comes with a king-size bed and monsoon shower, binoculars and balconies for taking in the views. An infinity pool and spa gives the space unity, while a restaurant serves fusion cuisine from Central America. Head offshore to spot dolphins in the Ballena Marine Park, or go inland to the wilds of the Osa Peninsula.

Kura Design Villas, Uvita de Osa (00 506 839 28150; Doubles start at US$440 (£293), including breakfast.

Tree House Lodge, Punta Uva

This playful resort on the Caribbean coast has more than a few unusual quirks. Four accommodation options, sleeping four to six, include a stilted treehouse that offers a back-to-childhood escape; a beach suite with a space-rocket-style bathroom; and a garden lodge that resembles a wacky wendy house. The final beach bungalow offers windswept seclusion, 80 metres from the shore. The Gandoca-Manzanillo Wildlife Refuge is nearby.

Tree House Lodge, Punta Uva (001 415 878 3786; The Garden Lodge starts at US$200 (£133), including breakfast. Sleeps six.

Arenal Nayara, La Fortuna

This collection of colourful casitas gazes up to the crater of Arenal. The country's most-active volcano is surrounded by a national park that's home to 850 species of birds, as well as monkeys and jaguars, making the lodge a prime spot for wildlife fans. The decor reflects the tropical surroundings, with brightly painted walls and furnishings, while the bungalows come with vaulted bamboo roofs, outdoor monsoon showers and balconies with hammocks and Jacuzzis.

Arenal Nayara, La Fortuna, Arenal NP (00 506 2479 1600; Doubles start at US$277 (£185), including breakfast.

Lapa Rios, Osa Peninsula

Former Peace Corps workers, John and Karen Lewis, moved from Minnesota to Costa Rica in the Nineties to develop a tract of rainforest into a conservation project and private reserve. The result was Lapa Rios, which pokes out of the canopy with 16 thatched bungalows, close to Corcovado National Park. Each lodge is open to the elements on three sides, with only a mosquito net separating the beds from the balconies. A communal pool and restaurant invite guests to trade tales of adventure.

Lapa Rios, Osa Peninsula (00 506 2735 5130; Doubles start at US$588 (£392), all inclusive.

Beach Estates, Santa Teresa

Rolling waves set the soundtrack to this exclusive coastal haunt on the Nicoya Peninsula. Located in Santa Teresa, a sleepy fishing village turned popular surfing spot, it has just two houses available for rent, both of which sleep eight. The newest is Beachwood, complete with clean lines, contemporary design and an infinity pool overlooking the beach. The second is Sandy Lane, spread over two floors of an open-sided wooden house, with the same spectacular views.

Beach Estates, Santa Teresa (001 310 774 0750; Nightly rental from US$550 (£367), self catering. Each sleeps eight.

Pacuare Lodge, Turrialba

The adventure at Pacuare Lodge starts with the journey. Opt either to raft along the white-water rapids of the Pacuare River or enter via "ground transportation" from San José, catching a minibus through the old capital of Cartago, to the town of Turrialba, before changing to a 4x4 in Santa Marta for the final bumpy descent into the resort. Once there, guests are rewarded with luxury bungalows, a gourmet restaurant, and activities from canyoning to horse-riding.

Pacuare Lodge, Río Pacuare, Turrialba (00 506 2225 3939; Doubles start at US$674 (£449), all inclusive.