This is a private reserve on a tiny spit of land on the Pacific side of Costa Rica, 15 kilometers from Jacó and 45 minutes from the Manuel Antonio National Park.
My suggestion:
Punta Mala is dedicated to agro-ecology and should be high on your list if you are more interested in eco-tourism than in just relaxing. To get there you need to know the time of the tides and it's better to go in the dry season.
My review
The Punta Mala peninsula is a peaceful and remote place where you can stay in small tent bungalows with a view of the ocean and near a pretty stream (and you can bathe in a magnificent waterfall).
During my stay in Costa Rica, I didn't have the chance to stay at Punta Mala but I did see the mangrove forests of this little peninsula which is the only wildlife reserve dedicated to protecting the Olive ridley sea turtle. As well as sea turtles there is a multitude of rare birds like toucans, caracaras and macaw, and sea mammals (whales and dolphins). A delightful place to explore!