BEYOND THE DEEP

The obscure and dangerous pursuit of diving into Earth through underground sumps, described by the cavers who plumbed the farthest known reaches of Mexico’s Huautla system.

If your idea of adventure is to swim underwater deep underground in utter darkness with no clue of what you’re going to run up against—then sump diving is for you. It certainly isn’t for everyone. But Stone and Ende make a good case for their obsession with the vastness of the Huautla system of caves and connecting sumps: an obsession, essentially, with pushing into the unknown for the chance of finding the glories of an azure sea underneath a half-mile of limestone or of surfacing into aircraft-hangar–sized chambers after swimming through tight tunnels of water. Here, the two tell the story of their siege on the system, describing the technical equipment they perfected for the dive—including a rebreather that forms a closed metabolic loop—and the logistical aspects of keeping cavers underground in hypothermic conditions for days at a time. The authors also include the personal side of the expedition, telling about the cavers who dropped out, or who peeled back from their goals, especially after one of the team died under peculiar circumstances. The most gripping material comes with the snafus: hair caught in equipment, the loss of vital tools, broken bones from falls, terrifying moments when the stirred-up silt reduces visibility to zero, too many brushes with drowning. (As cavers are fond of saying, there are no rescues, just body removals.) Always at play are the group dynamics, which flare brightly on occasion but on the whole remain remarkably bonhomous under circumstances that could only be described as insanely trying.

The tale of an activity inexplicable for anyone with even a hint of claustrophobia, yet also a distillate of pure adventure deep inside the world. (Maps)