Petrified Waterfall
From a distance this waterfall appears to have been frozen in time. But though it was formed by water spilling over the edge of the cliff, Hierve el Agua is solid rock.
https://en.wikipedia.org/wiki/Hierve\_el\_Agua
Photo: ben\_kitchener3, CC BY 3.0
https://commons.wikimedia.org/wiki/File:Hierve\_Agua\_-\_panoramio.jpg