When I go into caves, I think a lot about the juxtaposition of time. Travel on the surface is nearly effortless by comparison. To reach this point, a point never seen by human beings before us, we had to put in days of effort digging out the constrictions in the passages between, returning to the same project over months and gaining a few feet every day.

Even now, when the only limits that will stop you are your own, to reach this point is not easy. You must climb, crawl for hundreds of feet, negotiate vertical drops on and off rope, endure cold water and gritty mud, and make your way slowly through passages that few people ever have.

These passages that developed for their own purposes, none of which involve people. The floors are uneven. The ceilings are irregular, and often low. The walls are carved into alien shapes. The air is dusty and damp. Streams occupy the space insistently. A person may coexist with these things, but there is no illusion that you are an important part of such a place.

The juxtaposition of time is that to reach the place where I took this photo, we traveled in the cave for over an hour. There is approximately 150ft of solid rock above this place, and then trees, and then sky. If you begin at the entrance and travel to the nearest point on the surface, it is 150ft away, and it takes you only three minutes. But that last 150ft might as well be a mountain between the two.