Inside Chiquibul Cave

Plunging Through

Effort and elation propel caver John Wyeth through a watery canal in the Chiquibul cave system en route to the exit after eight days underground. On a recent expedition cavers mapped a vital link in this labyrinth of four huge caves carved through limestone in Belize and Guatemala by rainwater and the subterranean Chiquibul River.

It's April 30, 1999, my sixth expedition to the Chiquibul cave system. On each trip I feel I'm opening books in an underground library that has preserved records of dramatic climate change over time, of the lives of the Maya who once used these caves, and of numerous animal species, living and extinct. This trip will include geologic sampling to estimate the age of the caverns and the impact of regional tectonic motion. We also hope that Brown's dive will answer a question.

A World Below With gaping invitation a huge sinkhole called Nohoch Ch'en (Maya for "great well") hints at the presence of caves below the rain forest of Belize. Within one of those caves, a 25-foot-tall splatter-cone stalagmite sprouts petals of calcite. By measuring the decay of uranium isotopes in such stalagmites, geologist Joyce Lundberg estimates that the Chiquibul caves began to form at least 800,000 years ago.

Ninety minutes tick by. Finally bubbles spill up to the surface. Weighted with a hundred pounds of gear, Brown wallows out in knee-deep muck and calmly announces that after a dive of 200 feet through the sump he emerged into an airy gallery up to 160 feet wide. It proves to be part of Cebada Cave. We have our answer: Tunkul Cave is physically connected with Cebada to the west, a link that creates a single cave nearly 25 miles in surveyed length-by far the longest in Central America.

Proving that suspected link was a satisfying piece of a puzzle begun in 1984, when Chas Yonge and I first explored Tunkul. Surveying its passages, we wandered into an immense cavity. Our lights lacked power to show a ceiling or walls; we merely sensed boundaries in a night without a sky. Now named Belize Chamber, the room bulges on our map like an anaconda's meal. Measuring almost 1,600 feet long by 600 wide, it is the largest known cave room in the Western Hemisphere. Such revelations have rewarded me and my fellow cavers as we've surveyed the maze of Kabal, Tunkul, Cebada, and Xibalba, four hydrologically linked caves excavated by the Chiquibul River on the border between Belize and Guatemala.

Secrets Revealed Probing the slime of a stagnant pool, expedition biologist Jean "Creature" Krejca (above, at left) and Taco van leperen collect samples of bacterial fibers tinted red by iron oxides. Krejca and others have identified new living species of tiny spider-like ricinoidids and amblypygids, as well as larger animals, including a blind shrimp and a translucent crab. Ancient mammals also haunt the caves of Chiquibul. The 10,000-year-old bones of a bear lie in a regally columned tomb in Cebada Cave (right). Paleontologist Greg McDonald of the U.S. National Park Service believes that this is a female cub of the extinct species Tremarctos floridanus. "This find extends the known range of the species nearly a thousand miles farther south," says McDonald. "Either this bear was more adaptive to tropical climates or the environment in Belize was drier at the end of the last ice age than we thought." Maya people, too, once entered these caves to obtain water and to honor their gods. Clay whistles, grinding stones, incense burners, and altars are among the many artifacts logged by archaeologist Logan McNatt for the Belize Department of Archaeology. Near a flowstone wall in Kabal, Enrique Soquil examines a cracked olla (left), one of many large, plain pots left here by the Maya some 1,200 years ago. At that time tens of thousands of Maya lived in the now uninhabited rain forest above the cave.

But not all the revelations have been pleasant. In 1998 we spent a week in Cebada. After enduring chilly swims and body-size crawls through arduous Limp Passage, we followed the Chiquibul upstream, only to be stopped when the cave's ceiling dipped into the river at a sump. As I wrote annoyed comments in my sketchbook, caver Pete Shifflett searched for a bypass and biologist Jean Krejca grabbed an unlucky eel and stuffed it into a bottle of formalin. We named the spot Eel Sump and determined to dive it the following year.

Frozen in Time Forever draped in a calcite shroud, the bones of a bat adorn a room in Cebada Cave. Thousands of bat skeletons representing several species-including a large extinct vampire bat-rest here. Undisturbed by scavengers, the corpses decay slowly, leaving perfectly intact bones that date back 10,000 years or more.

On our return last spring, 14 of us hiked into the rain forest while the British armed forces helicoptered a month's worth of freeze-dried food, cylinders of compressed air, and other supplies to our surface camps at Tunkul and Cebada. We split into two groups. One lowered dive gear down a 130-foot shaft near the Belize Chamber. By entering here, we avoided lugging heavy gear through much of Cebada and the Limp. This group included the four cave divers (myself, Brown, Shifflett, and Krejca), who would swim the suspected sump link between Tunkul and Cebada. A second group entered Cebada and ferried supplies to Camp II, where they would meet us after our dives.

Belly of the Beast Struggling upstream through the guts of Cebada, Stan Allison (front to back), John Wyeth, Gosia Roemer, and the author haul diving gear along the mile-long stretch from Camp II to Eel Sump. Such treks through Cebada, some 500 feet underground, are limited to the dry season; a sudden river rise during wetseason floods could trap the team with no way out. Even the dry-season current is swift. Much of the way their feet don't touch bottom. Unable to see the razor-sharp rocks that lie below the surface, many of the cavers bear scars as souvenirs of the trip. Allison, Wyeth, and Roemer were members of the expedition's vital support crew. Hailing from as far away as Poland in Roemer's case and Indonesia in Wyeth's, they helped establish underground camps and transport scuba tanks and gear, sometimes lowering equipment on ropes down vertical shafts, then floating it downriver on inflated car inner tubes. Team members Pete Shifflett and Jim Locascio developed powerful lightemitting-diode headlamps to help beat back the dark.

Cathedral in Stone Soaring columns inspire awe in a passage of Cebada Cave called Mind Proddler. Geologic Studies suggest that this is the oldest of perhaps five cave levels cut by the Chiquibul River. Later levels were formed lower down, as earthquakes and tectonic motion caused periodic uplifts, which Miller calculates raise this area about three feet every 10,000 years.

Into the Light Daylight splashes a silent pool near the Zactun entrance of the cave named Xibalba, Maya for "underworld." These columns, which have taken 170,000 years to form, endure against annual floods that can raise the Chiquibul River 70 feet or more. The submerged river flows through Xibalba, then spills out from the cave in a rush of rapids at the base of a Guatemalan gorge. Like Kabal in the east, this westernmost of the system's caves holds one of the world's largest underground passages. For two miles it averages 260 feet across. Such intriguing features as vaulted rooms, tight tunnels, and watery sumps give these caves their appeal. As far as Miller's team knows, it has explored everything with air in it. What remains is to find the flooded underground links between Kabal and Cebada and between Cebada and Xibalba-goals that will bring the team back in the years ahead. Because air temperatures in these tropical caves average a mild 74°F, camp life is relatively pleasant. But diving into Tunkul Sump-the first cave diving ever done in the Chiquibul system-was otherworldly. For Miller, entering the chilly waters of the sump was "like being in outer space, where all is weightless, dark, and unknown."

Gift of a Vanishing River From the hills of Belize the Chiquibul River runs west into Guatemala before its waters join other streams and flow northeast to the Caribbean. Along much of its course it runs below ground, where it has carved some of the largest cave passages in the world. Explorers have mapped some 40 consecutive miles and suspect another 20 are yet to be found. Says lead researcher Thomas Miller, "It's like putting together a puzzle in the dark - and we don't know where the pieces are."

No End in Sight Celestial in size, the giant Sand Passage in Kabal, easternmost of Chiquibul's four caverns, broadens to 130 feet across. "It's so big it's hard to grasp that you're in a cave," says Pete Shifflett, shown standing near the right wall. Every wet season the rising Chiquibul River surges through this room, leaving new ripples on the ancient floor.

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Explore Chiquibul online through photographs and 360-degree IPIX images. A National Geographic team spent days on end shedding light on underground wonders. Get the picture through high-tech imagery, maps, and field notes.

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Reprinted from National Geographic, April 2000, without permission, hoping that they won't mind