PHOTO : SHUTTERSTOCK . COM 098
Yucatan also has cenotes . They are the natural karst wells filled with fresh water . A couple of them are specially equipped for swimming . E . g . the Ik Kil cenote located not far away from Chichen Itza . The karst holes have formed many beautiful caves . You can see them in the Rio Secreto natural park . Its name is translated from Spanish as a “ Secret River ”. A 5-kilometer underground river flows through caves that are 72 million years old . Before the tour , tourists are equipped with wetsuits and flashlights . Even the most ardent speleology fans claim that this is the place with some of the world ’ s most stunning stalactites and stalagmites .