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  Field Notes From
Mexico’s Poisonous Cave

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From Author

John L. Eliot

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From Photographer

Stephen Alvarez

In most cases these accounts are edited versions of a spoken interview. They have not been researched and may differ from the printed article.

Photographs by Stephen Alvarez

image: stones
In Mexico’s Poisonous Cave

Field Notes From Author
John L. Eliot
The best part of this foul cave was escaping it. For five hours a day we put up with toxic gases, rocks coated with acidic slime, and razor-sharp underwater crags and holes that tried to break ankles, slice boots, and upend us when we waded through the stream on the floor of the cave. At least none of us fell into “Jaime’s Surprise,” a 12-foot-deep (4-meter-deep) hole that swallowed one early caver and all of his gear.
At the end of each day I fairly flew out of the cave’s mouth, ripped off my respirator—try wearing a large rubberized leech on your face for five hours—and hit the mile-and-a-half trail to the river where we caught the boat to the town of Tapijulapa. There could be no more exquisite sensation than diving into that water. Once two of us floated the mile or so all the way down to the town. As engineer Dave Lester and I left on our last day, I turned my head and yelled at the cave: “Missed me!”
The sulfur demons in the cave conjure up a witches’ brew of poisonous gases. The most prevalent is hydrogen sulfide, the “rotten egg” smell that made our nostrils flare hundreds of yards from the cave. Concentrations of hydrogen sulfide above 250 parts per million can cause blood vessels in your lungs to boil. Respirators must be worn at all times. But you can get sick even with filters because the brain can become habituated to the gas without your realizing it.
One of the cave rooms with consistently high hydrogen sulfide readings is called Yellow Roses. On my last day three of us went in. My companions wore gas monitors, which immediately unleashed ear-splitting shrieks. Problem was, the maximum levels of hydrogen sulfide those particular monitors could record were 125 parts per million. And these scientists have been in Yellow Roses with other monitors that displayed MUCH higher levels.
“Two minutes!” Dave Lester warned me. So I took a quick look at the lovely sulfur rosette-like formations, listened to his explanations, and we fled. Once outside, I became so lightheaded that I had to sit down fast before I collapsed. “Dave, I REALLY don’t feel good,” I said. But my dizziness passed.
Just after dawn one morning I found myself hanging onto a cloth bag and a pulley attached to a polyethylene cable stretched about 200 yards (180 meters) over the Almandro River, to which no Corps of Engineers bridge-builders have yet paid a visit. “Zipline” is the vernacular for this rig these days, but I prefer Dave Lester’s more formal appellation: a Tyrolean Alpine Traverse.
As I whizzed over the rock-strewn Almandro, I was less concerned about what to call my transportation and more concerned about the tree looming up rapidly from the end of the line. “Twist! Turn your body!” the guys yelled...too late, as my shoulder slammed into the tree.

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