Cryptonomicon

Eventually the water rises up into the Bubble itself, but it rises slowly, because the pressure of the air in here has become quite high already. As the water climbs, it further pressurizes the bubble of air in which Goto Dengo and the others are trapped. The pressure of the air rises steadily until it becomes equal to the pressure of the water. Then balance is achieved, and the water cannot rise any more. Another kind of balance is being reached within their bodies, as the compressed air floods into their chests, and the nitrogen in that air seeps through the membranes of their lungs and dissolves into their bloodstreams.

"Now we wait," says Goto Dengo, and shuts off his acetylene lamp, leaving them in darkness. "As long as we do not burn lamps, there is enough air in this chamber to keep us alive for several days. Captain Noda and his men will spend at least that long tidying up the Bundok site, erasing all traces of our work, and killing themselves. So we must wait, or else his men will only kill us when we appear on the shores of Lake Yamamoto. I would like to spend the time educating you on the subject of caisson disease, also known as the bends."

***

Two days later they set off one last, relatively small dynamite charge, blowing a hole through the wall of the Bubble that is large enough to admit a human being. On the other side, the diagonal to Lake Yamamoto begins.

Rodolfo is more terrified than anyone else, and so they send him first. Then goes Bong, and then Wing. Finally Goto Dengo leaves the foul, used-up air of the Bubble behind. Within a few moments they have found their way into the ascending diagonal tunnel. They begin to swim uphill through total darkness. All of them are trailing their hands against the tunnel ceiling, feeling for the opening of the first vertical shaft. Rodolfo is supposed to stop when he feels it, but the others must also be alert in case Rodolfo misses.

They thud into one another in the darkness like a loosely connected train bumping to a halt. Rodolfo has stopped--with any luck, he has found the first vertical shaft. Wing finally moves forward, and Goto Dengo follows straight up the vertical shaft and finally into a bulb at its top where a bubble of air has been trapped. The bulb is just barely wide enough to accommodate four men. They pause there, all jammed together in a cluster of bodies, heaving as they exhale the nitrogen– and carbon-dioxide-tainted air that they've been living on for the last sixty seconds, and breathe in fresh lungfuls. Goto Dengo feels his ears popping as pressure is relieved.

They have covered only a small fraction of the four hundred and fifty meters that separate Golgotha from the lake horizontally.But half of the hundred-meter verticaldistance has already been covered. That is, the pressure of the air they are breathing in this chamber is only half of what it was in the Bubble.

Goto Dengo is not a diver, and knows very little of diving medicine. But his father used to speak of how caissons were used to send workers deep underwater, to build things or to mine. That is how he learned about caisson disease, and how he learned the rule of thumb that most men will not suffer its symptoms if you have them decompress for a while at half the original air pressure. If they stop and breathe for a while, the nitrogen will come out of the tissues. Once this is done, the air pressure may be halved again.

In the Bubble, the air pressure was nine or ten atmospheres. Here in the first chamber, it's more like five. But there's not much air in this one--just enough to let them breathe for fifteen or twenty minutes, and bleed nitrogen out of their tissues, and get lungfuls of air for the next leg of the swim.

"Okay," Goto Dengo says, "we go." He finds Rodolfo in the darkness and slaps him encouragingly on the shoulder. Rodolfo takes a series of deep breaths, getting ready, and Goto Dengo recites the numbers that they all know by heart: "Twenty-five strokes straight. Then the tunnel bends up. Forty strokes up a steep hill. Where the tunnel bends again, you go straight up to the next air chamber."

Rodolfo nods, crosses himself, and then does a somersault in the water and kicks himself downwards. Then goes Bong, then Wing, and finally Goto Dengo.