Barra Honda is unique among the National Parks of Costa Rica: its main attraction is a large, intricate system of limestone caverns, decorated with a multitude of capricious forms and figures.

The nearly flat mesa of the Barra Honda hill looms 300 m above the Tempisque valley and has its highest peak at 450 m altitude. Its base consists of a former coral reef dating back over 60 million years. Tectonic faulting uplifted it from its former seabed and rains created underground waterways. The constant dropping of rainwater on calcium carbonate has then created these underground art galleries – fancies of nature slowly grown over millenniums of years.

Until now only 19 of Barra Honda’s 42 caves have been explored. The cave system was only discovered in the late 60ies. Before that people believed that Barra Honda was a volcano. They took the whirring of bat wings for volcanic activity and the smell of guano for sulfur fumes.

The caves of Barra Honda are well preserved because their vertical entrances are difficult to negotiate. Nevertheless have human skeletons and pre-Columbian artefacts been found in the 30 m deep Nicoa Cave.

The deepest of the Barra Honda caves is Santa Ana which drops to 249 meters below surface, while La Trampa (the trap) has the deepest precipice – a 30 m vertical entrance. Speleologists and spelunkers from around the world are drawn to Barra Honda.

One of the largest and most beautiful caves is Terciopelo which along with la Cuevita, is the only one open to the public.

Source: http://nicoyapeninsula.com