Krubera–Voronya Cave: 2,224 Meters Beneath the Caucasus

In a photograph from the Arabika Massif, a caver hangs from a rope where a rocky hillside opens into a shaft. The opening is about 60 meters deep. It takes the caver from daylight into the first part of Krubera–Voronya, a natural cave in Abkhazia, in northwestern Georgia. A 2024 expedition reported a total depth of 2,224 meters, or about 7,297 feet. That is the vertical difference between the top and bottom of the surveyed cave system. Reaching the deepest point involves a much longer trip through rock, with part of the route underwater. The mountain helps explain the scale. Krubera opens high above the Black Sea in a massif made largely of limestone. Rain and snowmelt can enter through cracks and dissolve the rock as they move through it. Over time, some of those cracks widen into passages that carry water farther down. Geologist Alexander Klimchouk describes a connection between the high ground where water enters the massif and springs near the coast, including springs that discharge underwater. The system can drain from the mountains toward the sea through routes largely hidden inside the rock. Below the entrance, steep shafts are separated by shorter passages that wind between them. The photograph from the Fartuk shaft shows a caver on a rope about 1,340 meters down. Even at that point, there are nearly 900 meters of vertical difference left before the surveyed low point. The route also crosses flooded passages called sumps. Water can rise or fall with snowmelt and rainfall, changing where a diver can enter a sump and which stretches of the cave are dry. Teams exploring the lower cave have had to move ropes, food, warm clothes and diving equipment through the same passages they intend to survey. In 2004, an expedition reached 2,080 meters, and Krubera became the first known cave explored beyond two kilometers in depth. Farther down, the route led into a flooded passage called Two Captains. Cave diver Gennady Samokhin describes reaching a constriction there where he had to turn sideways and adjust his tanks to fit through. In his account of the 2012 expedition, he recalls equipment staged at camps on the way down, including one nearly two kilometers below the surface. Even getting the diving gear to the water took a coordinated effort. The dive itself was only the final stage of a trip that also required hauling the gear back out. In Two Captains, Samokhin remembered that the level of the water had changed between visits. Marks the team had made near the sump helped them compare conditions from one expedition to the next, even when some marks were submerged. Surveying the cave adds another task. Teams measure the distance and angle between points as they work their way through the passages. Those measurements can be used to calculate how much elevation the route gains or loses. A connected opening higher on the slope can change where the depth measurement starts. A dive can change where it ends. Repeat measurements can also revise the total even when the explorers are traveling through familiar rock. That helps explain why the last few meters in the record are debated even though the overall depth is beyond question. In August 2024, an expedition led by Samokhin reported 2,224 meters after a new survey. Caver Primož Jakopin also reported a revised depth of 2,209 meters for Veryovkina, a separate cave in the same massif. Guinness World Records still credits Veryovkina with 2,212 meters, the figure from its March 2018 expedition. Krubera leads on the newer published survey figures, while Guinness recognizes the earlier Veryovkina result. Both caves drop more than two kilometers, and their proximity gives researchers a chance to compare how water has carved deep routes through the same mountain range. Some of Krubera’s discoveries are small enough to miss in the beam of a headlamp. In 2010, biologists Alberto Sendra and Ana Sofia Reboleira studied invertebrates from near the entrance to a sump more than 2,100 meters down. They found species with reduced eyes and pigmentation, including animals adapted to living in water underground. Their survey also found the greatest variety of species near the bottom of the entrance pit, where plant debris and other material from the surface can collect. Water carries some organic matter farther into the cave, helping sustain life at depths where there is no sunlight. That work also recorded a change in temperature. During the sampling period, the team measured roughly 2 degrees Celsius in the upper cave and 7.5 degrees near the final sump they sampled. The readings give a sense of the conditions that cavers and the animals they study encounter. Even near the bottom, the water was cold enough that the expedition had to account for prolonged exposure on top of the difficulty of moving through a flooded passage. The map pin marks the approximate location of Krubera’s main entrance in the Ortobalagan Valley. One photograph looks toward that entrance from the hillside, and another shows the separate Arbaika opening into the connected system. The third takes you down to the Fartuk shaft. Together they show the difference between finding a way into the mountain and tracing where that opening leads. The deepest surveyed point lies far below the scene in any of the three photographs, at the end of a route that cavers have been measuring and revisiting for decades.