The Río Umajalanta, which disappears beneath a layer of limestone approximately 22m thick, has formed the impressive Umajalanta Cavern, of which 4.5km of passages have been explored. Inside are some spectacular stalagmite and stalactite formations and waterfalls, as well as a resident population of vampire bats that have produced an impressively large pile of steaming guano over the years.
The 8km one-way walk to the cavern entrance takes two hours from the village, with plenty of dinosaur footprints to inspect on the way.
Only enter the cave with a guide, as it's easy to get lost. The exciting descent is moderately physical and you must expect to get both wet and dirty; there are several parts where you need to crawl and wriggle to get through and a couple of short roped descents. Make sure you have good nonslip shoes on. You eventually descend to an underground lake and river, which is populated by small white, completely blind, catfish. The ascent from here is fairly easy, as it takes a more direct route.
There are numerous other caverns in the area, most of which are virtually unexplored.
