Although Barra Honda National Park covers 2,295 hectares, its reason for being is not what lies on the surface, but the geological treasure housed below. This is the only park in the country that protects underground caverns.

To date, 19 separate caves have been discovered in the limestone ridge that makes up the Barra Honda formation. The entrances to these caves are all vertical. Therefore, ropes and climbing equipment are necessary for those who are interested in exploring this subterranean world. Cave depths vary from 21 to 240 meters.

In addition to stalactites and stalagmites, the wide variety of other curious geological formations inside these caves have given rise to the following descriptive names: soda straws, cave grapes, curtains, terraces, pearls, flowers, needles, and even fried eggs! Compared to many other caves with horizontal entrances, the geological features of Barra Honda are in excellent condition owing to the difficulty of access.

The natural vegetation that once covered much of the park is sadly not in perfect condition, due to deforestation and cattle ranching, nor is there a well-marked system of trails to the few decent patches of forest in the park.

Admission policy: Spelunking in Barra Honda requires previous permission, which can be arranged through the Park Service offices in San José (Telephone: 192).

To get there: From San José, take the Inter-American Highway north just past the entrance to Las Juntas de Abangares, look for the sign indicating the left turn to the Tempisque Ferry. Once across the river, continue on for about 12 kilometers before taking a right turn to the village of Barra Honda (also known as Nacaome). Continue on towards the village of Santa Ana and follow signs for the park entrance.

Climate: Hot and dry from December through April, and hot and humid during the rainy season.

History: During the past 70 million years or so, nature has patiently worked to create the remarkable system of caves at Barra Honda. First, millions of years were necessary to form the marine limestone deposits derived from ancient coral reefs. Then, seismic activity along local fault lines was responsible for raising the ridge above sea level where rain water and atmospheric gases could combine to dissolve away portions of the rock, while also leaving calcium deposits in an endless pattern of strange shapes inside the still-forming caves.

As recently as 1967, it was still a matter of debate whether or not Barra Honda Mountain was a volcano. Credibility was given to this belief by the foul odor and strange sounds -- likened to the roar of a steam engine -- that emanated from one of the "craters" on top of the ridge. As explorations of the caverns continued it became obvious that volcanism had nothing to do with the formation of Barra Honda and the opening that produced the smells and noise turned out to harbor a tremendous quantity of bats. The odor came from the accumulated guano and the "roar" was the sound made by the fluttering wings of tens of thousands of these creatures of the night.