Patience was the greatest virtue they had to display in the infernal labyrinth. In some cells, the researchers had to crawl on their stomachs, in others their presence was lost in the vastness. Some of the chambers in this cave complex, which stretches for miles under the rainforest of the huge island of Borneo in Southeast Asia, are of extraordinary size, in some places exceeding 60 meters in height. They were there to validate a scientific theory with methodical sampling. It was painstaking work that had to be done drop by drop.

For three weeks in November, Christos Pennos, a geologist and researcher at the University of Bergen, Norway, participated in a multi-person international scientific expedition of the British Speleological Society to Gunung Mulu National Park, Malaysia. The goal was to test theories about the creation and evolution of the spectacular caves of the Clearwater Cave System.

They had to collect drops of water from the walls, as well as moisture from the air, and then analyze their physical and chemical characteristics. “The scientific community knows that humidity plays a role in the dissolution of the cave walls, but in this case we wanted to test to what extent this happens,” Mr. Pennos tells K. “It was a laborious process that was carried out with perseverance and patience.”

The theory of Andrew Farrard, a British Geological Survey explorer and a key member of the expedition, is that the humidity in this cave complex hastened the dissolution of the limestone rock and played a key role over time in shaping the chambers of such large dimensions. Part of this complex is the world’s largest Sarawak chamber, over 600 meters long and 115 meters high, discovered in January 1981 by British speleologists. A member of this pioneering group was retired explorer Andy Ivis, who this year, at the age of 75, was also appointed to lead a recent expedition that included Mr. Pennos.

“I once caught him in a cave because every team has a different schedule. I saw him move like he was choreographed, always neat, clean, it was an experience to see him move in space,” says Mr. Pennos. The caves that Anti Ibis explored in the UK could not be compared in size to the caves in Malaysia. “I remember him describing to me what it was like when he was first in Borneo and suffocating,” adds the Greek researcher, who was accompanied on this mission from Norway by professor emeritus at the University of Bergen Stein Erik. Lorien.

Since 1978, numerous British missions have focused on this parallel world in Borneo. Despite the systematic research that has been carried out since then, it is believed that not all of its secrets have been revealed, so from time to time groups of experts return to find new tunnels or understand the processes that led to the creation of the cave and their expansion.

The expedition, in which Mr. Pennos participated, set off every morning from his base in the National Park. A local driver took them from the river in a motorized dugout to the places they wanted to go. In some cases, they also had to walk through the jungle, through passages littered with leeches. They spent long hours collecting samples in various places, near and far from the entrances to the caves, in the holes where the air currents pass, next to the deposits of bat droppings, as well as the swallows that nest in impressively large populations in these places. Drops of about 10 to 15 ml were collected from each point into vials. This diversity of sample will allow them to build a more complete picture of the various conditions prevailing in the vast complex.

To collect moisture from the air, they used a bottle of frozen water. It was hung in different places of the caves and, as soon as it sweated, the moisture condensed on its walls was collected. They could have used specialized pumps for the same purpose, but opted for simpler means to avoid potential material breakdown.

Many sample measurements had to be taken immediately while they were still in the field because the data of interest to them changes over time. The main measurements included the calculation of PH and electrical conductivity. Similar analyzes and experiments with calcium carbonate were carried out on more accurate instruments after returning to the base. Scientific research and analysis will continue in the UK to reach final conclusions.

Christos Pennos, a geologist and researcher at the University of Bergen, has been involved in international scientific exploration of the Clearwater Cave Complex.

Mr. Pennos also found samples of volcanic ash in the three caves, which had been deposited as a layer of mud. He will send them to a specialized laboratory in Pisa, Italy, for further analysis. The theory is that they appeared as a result of volcanic eruptions in the Philippines and were carried there by river water flowing through the cave complex.

The Greek scientist has significant experience in researching ice caves in Europe. In recent years, together with Greek and Romanian speleologists, they have been collecting ice cores with drills (cylindrical samples obtained by drilling a layer of ice), which seek to reveal to them, after special analyzes, information about paleoclimate, climatic conditions that existed in earlier geological periods, thousands of years back.

Ice cores act as a database that can store the paleoclimate information that scientists are looking for. However, as they discovered, these precious secrets of the caves are in danger of disappearing. The nature of the climate in recent years and more intense weather events have accelerated the melting of ice reserves in caves not only in Greece, but also in Croatia, Romania and Slovenia.

As Mr. Pennos explained to K, the samples of organic matter found in each ice wall (pieces of leaves or wood, some animals that might be trapped there, and bat excrement) can be radiocarbon dated from – 14 to Help accurately determine age. Then, by studying the ratio of oxygen and hydrogen isotopes in ice samples, they can draw conclusions about the climate that prevailed at a particular time period. He has done similar ice imaging in Norway, and in Greece, his first relevant mission, along with other researchers, was at the Falakros Snow Hole, one of the deepest ice caves in the country 18 km northwest of Drama, which reaches -111 meters.

“Snow Hole” consists of three parts. First, the explorers must descend 60 meters into a loose ravine. Through a hole in the upper layer of ice and another 20 meters downhill, they are led into a dark room where the temperature is one degree Celsius.

The conditions Mr. Pennos encountered in the Malaysian cave complex were completely different. “It was very hot, 22 degrees Celsius, which, combined with humidity close to 90%, created a stuffy atmosphere,” he says. Because of the tropical climate, it rained every afternoon and their clothes were constantly wet. All day they carried the smell of mold. There were other, unprecedented for him meetings in this new environment. “The snakes could be seen even a kilometer deep into the cave. There were very large spiders, almost the size of my palm and more, centipedes up to 20 centimeters long, and dolichopods, also known as cave locusts, which were twice the size of what we have in Greece,” he says.

The sheer size of the wards on the island of Borneo filled him with awe, but as he explains, he was quickly overcome by a sense of self-preservation and was more cautious than usual. He says that the slightest accident there could have had big consequences, since the area is quite remote, and going through the jungle until they got to the entrance was not the easiest thing to do. After so many expeditions to caves and dungeons in Greece and abroad, entering this parallel world no longer excites him. But he notes that even now, every time he goes out into the natural light, he experiences an inexplicable euphoria.