Caves form in many types of rocks, and through several different processes, collectively called “speleogensis.” But the largest caves, and those most frequently found, are formed in limestone, when the natural acid in rainwater dissolves away the rock leaving behind cave passages. These are called “solution caves,” and the porous limestone environment that supports them is called “karst.” Karst exists in most parts of the world to some degree, and is a prominent feature of places like the Nullarbor Plain in Australia, Southern China, the Southeast United States, and Mexico in the Yucatán Penninsula. There are probably millions of caves on this planet, but we know of just a small fraction of them. Amidst telescopes and microscopes, satellites and submarines, we have tools to see big and small and up and down, but almost nothing that can allow us to see into the caves, other than going there and looking ourselves. Sometimes, this feels like what it might be like to go to the moon, something I thought this picture helps to capture. With @henryfrawleyfulcher. #caveexploration #cenotes #rivieramaya #tulum #playadelcarmen #innerspace #wetpixel #uwphotography #earth #cavediving #cavedivingphotography