Around 20km south of the Lago de Yojoa is the entrance to the Cuevas de Taulabé, a network of underground caves with unusual stalactite and stalagmite formations. Admission includes a guide – a tip may get you to some of the less-visited areas. So far the caves have been explored to a depth of 12km, with no end in sight.
The first section of the caves has lights and a (sometimes slippery) cement pathway: wear appropriate shoes.