See inside Slovenia's famed underground caves, where researches float down hidden rivers and past otherworldly formations. https://on.natgeo.com/2L37gv3

See inside Slovenia's famed underground caves, where researches float down hidden rivers and past otherworldly formations. https://on.natgeo.com/2L37gv3 

https://twitter.com/NatGeoTravel/status/1147339419227213826