The Gouffre Berger cave, located in France, was discovered in 1953 and was named in honor of the first researcher, Josef Berger. The general length of the high passages is about 32 km. This is the first cave in the world, whose mines were examined at depth of more than 1,000 meters. At present, the maximum depth of the excavated mine is 1 323 meters.
The cave structure is incredibly complicated from a technical point of view. To get up from their deepest pit to the surface of the earth, the researchers need at least 15 hours. The main danger for the scientists is the sudden flood, which has cost 5 researchers. This is why Gouffre Berger is often referred to as a killer cave. One can not predict when and where in the cave will be flooded. At present the researchers know 9 natural inputs into the cave, which look as a vertical column with the average depth of 300 meters.
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