The cave complex was discovered by the speleologists of the Lviv speleological club "Cyclope" in 1966. It was entirely unknown before then.[7] There have been more than 50 expeditions since then, but exploration has slowed significantly in recent years, and very little surveying is currently being done.[3] The cave is located very close to the Priest's Grotto or Ozerna Cave, the eleventh-longest cave in the world at 130.4 km (81.0 mi), but the two caves have not yet been found to be connected.[1]
The entire cave lies under a 2 km square area in a layer of Neogene period gypsum that is less than 30 metres (98 ft) thick.[7][9] The passages tend to be fairly small, no more than 3 metres (10 ft) wide and 1.5 metres (5 ft) tall for most, although at intersections they can be up to 10 metres (33 ft) tall.[7] They are often choked with mud. They comprise a dense network on several levels, making Optymistychna known as a "maze cave".
Optymistychna's gypsum bed is topped with a limestone layer, which has seeped through into the cave via erosion and formed into calcitespeleothems.[7] At other places, the gypsum has formed crystals, often tinted a multitude of colors by mineral salts. In some areas, large gypsum rosettes have formed, colored black by manganese oxide.[7]
Notes
^This English transliteration was used during the Soviet era but is now deprecated.
^Guden, Bob. "World's Longest Caves". Caver Bob. Archived from the original on May 15, 2006. Retrieved 5 November 2020.{{cite web}}: CS1 maint: unfit URL (link)
^Guden, Bob. "World's Longest Caves". Caver Bob. Archived from the original on May 15, 2006. Retrieved 5 November 2020.{{cite web}}: CS1 maint: unfit URL (link)