Krubera Cave

Since Jules Verne wrote his influential novel “Journey to the Center of the Earth,” the aim to discover the deepest place below the surface has sparked the imaginations of generations of explorers, adventurers and scientists. Those in search of the deepest known cave on the planet are always leading to Georgia’s breakaway region of Abkhazia. Deep in the mountains of the Arabika Massif, these record-breaking caves can be found—the four deepest caves in the world, including Krubera Cave (also known as Voronya Cave, just to keep it interesting), second-deepest in the world, to nearby Veryovkina Cave.
Krubera Cave is one of five caves in the Arabika Massif mountain block to reach depths more than 1,000 meters. It is believed that the caves of Arabika Massif, including Krubera Cave, were formed as the mountains began to rise approximately five million years ago. The Arabika Massif, the home of Krubera (Voronya) Cave, is one of the largest high-mountain limestone karst massifs in the Western Caucasus. It is composed of Lower Cretaceous and Upper Jurassic limestones that dip continuously southwest to the Black Sea and plunge below the modern sea level. Among several hundred caves known in the Arabika Massif, fifteen have been explored deeper than 400 m and five deeper than 1,000 m.
The Arabika Massif in the Western Caucasus constitutes one of the largest karst massifs on Earth, but despite its enormous potential to scientists, the area, including Krubera Cave, has been woefully under-explored. One of the reasons is the remoteness of the area, which is only accessible for up to four months a year, but the main obstacles for scientists have been the numerous political conflicts in Abkhazia, which continue until today.
The cave system that includes Krubera starts high in the mountains at approximately 2,256 meters. The direct physical connection of Krubera Cave with the Arabikaskaja System is a sound possibility, although not yet physically realized. Krubera Cave’s Arabika Massif mountain block was written about in the early 1900s by Edouard-Alfred Martel, a speleologist from France. He published papers after visiting the massif. In 1909 and 1910 Alexander Kruber began to study Arabika. He published writing about Arabika. Krubera Cave was later named after him. From the early 1910s to 1960 exploration of Krubera Cave was mostly ignored by the geology community. In the 1960s it was discovered that Krubera Cave could reach more than 310 meters. In the 1980s exploration of Arabika Massif began to more common, led by Alexander Klimchuk. By 1987 the cave had been explored as deep as 340 meters.
The difference in elevation of the cave’s entrance and its deepest explored point is 2,197 ± 20 meters (7,208 ± 66 ft). It became the deepest-known cave in the world in 2001 when the expedition of the Ukrainian Speleological Association reached a depth of 1,710 m (5,610 ft) which exceeded the depth of the previous deepest known cave, Lamprechtsofen, in the Austrian Alps, by 80 m. In 2004, for the first time in the history of speleology, the Ukrainian Speleological Association expedition reached a depth greater than 2,000 m, and explored the cave to −2,080 m (−6,824 ft). Ukrainian diver Gennadiy Samokhin extended the cave by diving in the terminal sump to 46 m depth in 2007 and then to 52 m in 2012, setting successive world records of 2,191 m and 2,197 m respectively.
Cutting a jagged path through the limestone of the Arabika massif on the edge of the Black Sea, the “trail” to Krubera Cave drops down a chain of pitches, cascades, and pits—some more than 100 meters (328 feet) deep—connected by narrow rift passages called meanders. Krubera Cave is a deep, mostly vertical cave system. Passages in the cave system can be narrow and difficult to pass or wide and very large. In order to explore the caves completely cave divers need to be prepared to put on scuba gear because tunnels in the caves can sometimes become flooded. Flooded tunnels are referred to as sumps. Some of the passageways in Krubera Cave had to be widened to make it possible for cave divers and explorers to venture further.
A number of endemic fauna has been found at all levels of depth within the cave, including spiders, scorpions, beetles, as well as stygofauna like shrimps and amphipods. There are 12 arthropod species in Krubera Cave and a beetle called the Catops Cavicis that is endemic. The deepest living terrestrial animal found on earth can be found in Krubera Cave. This is a 3mm cellembole with no eyes and is believed to survive on fungus and organic material. It can live as far down into the earth as 1,980 meters.
The Ortobalagan Valley extends along the crest of the Berchil’sky anticline, which gently plunges northwest. The cave entrances are aligned along the anticlinal crest but the caves are controlled by longitudinal, transverse, and oblique fractures and faults and exhibit complex winding patterns in the plan view, remaining largely within and near the anticlinal crest zone. The caves are predominantly combinations of vadose shafts and steep meandering passages, although in places they cut apparently old fossil passages at different levels (e.g., at −2,100–2,040 m (−6,890–6,690 ft) in Kujbyshevskaja and Krubera caves, −1,200–1,240 m (−3,940–4,070 ft) and −980–1,150 m (−3,220–3,770 ft) in the non-Kujbyshevskaja branch of Krubera Cave, etc.). The deep parts of Krubera display a more pervasive conduit pattern with a mixture of phreatic morphology, characteristic of the zone of high-gradient floods, which can be up to 400 m above the low-flow water table.
The Upper Jurassic succession begins with thin-bedded Kimmeridgian–Oxfordian cherty limestones, marls, sandstones and clays, which are identified in the lower part of Krubera Cave. Above lies the thick Tithonian succession of thick-bedded limestones with marly and sandy varieties. Sandy limestones are particularly abundant through the upper 1,000 m sections of deep caves of the Ortobalagan Valley.
A cave in Mexico’s Oaxaca region is set to be explored in 2017 and some believe it may be deeper than Krubera Cave’s depth record. However there are many more caves to be explored around the world that some believe will prove to be even deeper.