National Geographic : 2011 Jan
nettles. As our time and supplies begin to run out, Howard decides the moment has come to send an advance team ahead to the Great Wall of Vietnam, to see if an assault is really possible. e wall lies more than a mile away at the end of a corridor shaped like a V with a foot-deep trench of water at the bottom. Mud walls, sticky as peanut butter, rise 40 feet high on either side. It is not possible to walk in the trench, only to stumble. By the time you reach the wall, you're so covered in mud you appear to have gone swimming in chocolate pudding. The cavers named this passage Passchendaele, after the trench warfare battle of World War I in which the Allies lost 310,000 soldiers to gain only ve miles of ground near the Belgian village of Ypres. Climbing an overhanging 200-foot-tall wall of mud is technical, risky business, so you need just the right type of madmen. Luckily, Howard has handpicked Gareth "Sweeny" Sewell and Howard Clarke for the advance team. e two have been caving together for 20 years in the nastiest potholes in England. Clarky is a bull semen salesman, and Sweeny is a legal special- ist who somehow convinced his wife that they should sell their one and only car so he could keep heading o on caving expeditions. e rst day at the base of the wall, as Clarky belays, Sweeny begins boldly working his way upward, drilling hole a er hole. Almost all of the holes are too hollow to hold a screw from which to hang their ropes. For 12 hours they jabber in their expletive- laden Yorkshire vernacular---"ez bloody crap covered wit mood," Sweeny says at one point. Neither says a word about the true dangers of the task. Were any of the six-inch screws to pop out, the rope Sweeny is hanging on would lose its anchor and he'd likely zipper the rest of the screws and plummet to his death. On the second day of the climb, a er biv- ouacking at the bottom of the wall for the night, Sweeny returns to his previous high point, with Clarky belaying again. Soon enough the whirring of his drill echoes through the domed blackness, Sweeny so high up we can see only the glim- mer of his headlamp. At two in the a ernoon--- of course it doesn't matter a bit what time it is when it's dark 24/7---a er 20 hours of drilling holes and climbing higher, Sweeny nally disap- pears over the wall and some minutes later we hear: "AAIIOOOOO!!" Clarky ascends the rope next, then yells down for me, the words bouncing through the cave: "Well, ye comin' up or wat!" At the top of the Great Wall of Vietnam we can literally see light at the end of the tunnel and start howling our heads o . e rest of the expe- dition will later tell us that they actually heard our hallos more than a mile away in the cave. Measurements made at the top of the wall will reveal that from the bottom of Passchendaele to the ceiling is 654 feet. It's just the three of us now, exploring. No human has ever been here before. We drop down o the backside of the Great Wall and begin ascending a staircase of rock toward the exit. "Will ye look at deese!" roars Clarky, kneel- ing beside a dried-up pool. Sweeny and I gather around. Inside the pool, illuminated by our headlamps, are cave pearls. Cave pearls are formed when a drop of wa- ter from the ceiling hits the limestone oor and throws up a speck of rock. is grain is jostled in its little cup of stone every time a drop hits it. Over thousands of years, a solid, almost per- fectly round calcite pearl is formed. Pearls are rare and in most caves are no larger than a marble. e cave pearls here are the size of baseballs, larger than any the cavers have ever seen. ( eir preternatural size may be due to the enormous distance the ceiling waterdrops fall.) "I 'ereby christen this passage Pearl 'arbor," Clarky announces. Twenty more minutes and we're scrambling up and out of the cave. It is raining in the jungle. We hack our way far enough out into the for- est to recognize a horizon and determine that this is not just another skylight, but that we have discovered the end of Hang Son Doong. Sweeny and Clarky are far too humble to openly express that we've just completed the rst push through what is very likely the largest cave passage in the world. j At the Great Wall of Vietnam, we howl our heads off. The rest of the expedition can hear us more than a mile away.