Deep, dark and mysterious, caves inspire both enigma and fear. To those terrified of the dark, getting lost in a cave, with the echo of water dripping, can be the worst nightmare.
And then there are those who'd rather spend their entire lives away from the sun, bedazzled by these hollows of the earth. From subterranean limestone caverns to underwater recesses inside the bowels of aquifers, caves are the haunt of spelunkers, that tribe of adventurers who never tire of the darkness, the smell of bat guano, and the adrenalizing taste of discovery.
Explore these images of caves around the world, sourced from Flickr.