People have been exploring Jaguar Cave since prehistoric times, but the system is so vast that unknown conduits and million-year-old piping are still being discovered. Moving again, we crawl and climb and pull and push, eventually peeping out into a large cavern. Smith has a saying that "caves either drop, pop, or stop." This one pops. Even with our headlamps on high beam we can barely make out the walls around us. The chamber is the size of a small but very high-ceilinged gymnasium.
"Look up and right," directs Bobo. As we shine our headlamps onto a wet rock wall, a rope appears, dangling out of the upper blackness. One by one we ascend the rope. At the apex of the domed cavern we traverse along a sloping ledge over the invisible seven-story drop we've just climbed, then enter another tunnel. It's large enough that we can stand up and walk for more than a thousand feet before the passage is solidly plugged by a pile of boulders and dirt—a breakdown, where the ceiling has collapsed.
This is as far as any human has probed. Our team believes the passage continues on the other side of the breakdown, so our goal is to "push" the cave: Go beyond what is known into the invisible unknown. We divide into two parties, mappers and diggers. Smith and Bobo will survey the borehole; I volunteer to be a digger.
When it's my turn, I lie down on my belly and shimmy to the end of a hole beneath the breakdown. Flat on my stomach, the ceiling pressing down on my neck, walls forcing in on the sides, I hold the shovel stretched out in front of me and furiously jab at the dirt wall. Chunks of earth fall all around me as I dig like a berserk badger. Several times I fill a drag tray, pushing it beneath me and then backward with frog kicks, where it is emptied by the other cavers. But soon the hole is too narrow, and I dispense with the drag tray, instead using my hands as scoops to maneuver the dirt around my body.
After 30 minutes I've moved perhaps five feet forward, my arms are aching, and I'm soaked in sweat. I'm about to back out when my shovel breaks through. I feverishly round out the hole and cram my head through. There is a low, triangle-shaped crawlway ahead of me. Surging with adrenaline, I try dragging myself into this new passage, but my chest gets stuck.