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.
Summary:
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!