Explore Ojo Guareña—one of the most extensive karst cave systems on the planet—and walk in the steps of our ancient ancestors http://on.natgeo.com/2FlINyC pic.twitter.com/s6c2m79CbC

Explore Ojo Guareña—one of the most extensive karst cave systems on the planet—and walk in the steps of our ancient ancestors http://on.natgeo.com/2FlINyC  pic.twitter.com/s6c2m79CbC

https://twitter.com/NatGeoTravel/status/971838308035723264