Not far from the village of Korolevka in Ukraine is the longest gypsum cave in the world - Optimistic. It was opened in 1966, and to date, 230 kilometers of cave length have been mapped. Until the end, she has not yet been examined.
About 20 million years ago, the ancient shallow sea was in these parts, but then it receded, and numerous earthquakes caused cracks in the mountainous city. Since the breed consisted mainly of gypsum, it was not difficult for the water to grind huge underground labyrinths of the Optimistic cave in it. The caves tried to pass through the mazes of the cave back in 1965, speleologists from Lviv, but they were blocked by a siphon filled with water. Only a year later did they attempt to get through it. So the first 400 meters of the cave were examined. With each new attempt, scientists examined 100-1500 meters of the cave, skeptical colleagues called them "optimists", believing that the length of the cave is only a few kilometers. From here came the name of the Optimistic cave.
With each new expedition, exploring the caves was becoming increasingly difficult, so the base camps in the cave began to be built for relaxation. In total, there are 15 camps, of which the farthest is called "Oasis", it has a water tank, food supplies for kitchen utensils and places to sleep. The camps have everything you need for multi-day expeditions. Previously, canisters with water had to be carried with them, but with the discovery of water sources in caves, the work of researchers was greatly simplified.
The labyrinths of the Optimistic cave are located at a depth of about 20 meters, it has a lot of clay, from which craftsmen make sculptures directly in the cave. You can also see stalactites, various cottage industries, helictites, small lakes with clean water. Going to the cave will leave indelible impressions for any experienced traveler. But narrow passages and musty air will still make themselves felt, and I will rather want to go outside and swallow fresh air and have a good rest after a grueling trip.