Barra Honda National Park

Barra Honda National Park, in western Costa Rica, protects a cave system formed when Miocene-era islets were raised above the Tempisque River plains. Rain filtering through limestone over 70 million years carved the caverns, which are only about 50 percent explored. The park was created in 1974. It receives 1,970 mm of rainfall annually and averages 28 °C. The caves house rare species such as blind salamanders and endemic fish adapted to darkness, as well as bat colonies.