Underground Emergency

In one of the world's biggest caves, a scientist gets in over her head.

Deep inside the mountain, we hear the sound of a river. The four of us—all researchers who study caves—are exploring Quankou Dong, or Big Spring Cave, in a remote, mountainous part of China, just south of Chengdu.
The “big spring” is a river that runs through a passageway from one end of the enormous cave to the other. Along the way, it churns into class 4 rapids. Hours earlier, we’d entered through a dry passage. Now, it’s full of water, rising fast.
The cave’s entrance is stunning: 100 feet wide, 300 feet high. Once inside, you pass through Cloud Ladder Hall, a 16-acre room so high it has its own weather system. One of the largest cave chambers in the world, it rises more than 1200 feet, though its roof is typically hidden by clouds.
We first went inside Quankou Dong in 2008, after it’d been discovered the year before, and we had been back several times. On one occasion, I slipped on a rock, fell in, and got tossed around in the rapids! It wasn’t funny at the time—class 4 rapids are very difficult to maneuver and can be incredibly dangerous—but my colleagues and I laugh about it now.
This year, we’re undertaking an epic 24-hour exploration. Since you can’t rent a car in Tongzi, we pay a driver 300 yuan to drop us off and then pick us up the following day. We’re wearing kneepads, wind-resistant PVC suits, and helmets equipped with powerful caving lights. Our packs are full of climbing equipment. Around 2 p.m., we arrive at the mouth of the cave.

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