Unlike the volcanic stone found throughout northern Costa Rica, Barra Honda area of the Tempisque Basin, where the Nicoya Peninsula joins the mainland, a limestone foundation was discovered. Water has cut extensive caves through the small mountains of the park, and this is its best known feature. However, the park also has well maintained hiking trails. The protected tropical dry forest (though mostly secondary) within its borders is some of the last in the world, and very different from the rain and cloud forests that attract many ecological tourists to Costa Rica. Stalactites, stalagmites and other calcareous formations of the more than 40 limestone caverns are the main Barra Honda’s National Park attractions. The caves are all in good condition because their vertical entrances are difficult to negotiate. This is also why you need climbing gear and a guide. The network of hiking trails used to access the caverns are great for exploring one of the rarest habitats on earth: tropical dry forest.