Optymistychna Cave

The Optymistychna (Ukrainian: Оптимістична, lit. 'optimistic', also known as Peshchera Optimistitscheskaya)^[2][a] is a gypsum cave located near the Ukrainian village of Korolivka, Chortkiv Raion, Ternopil Oblast.^[3] Approximately 264 km (164 mi)^[4] of passageways have been mapped within.^[1] As a result, it is the longest cave in Europe and the seventh-longest cave in the world,^[5] after Mammoth Cave, Sistema Sac Actun, Jewel Cave, Shuanghedong and Sistema Ox Bel Ha. It is also the longest gypsum cave in the world.^[1][6]

Optymistychna
Location	near Ukrainian village of Korolivka, Chortkiv Raion, Ternopil Oblast
Coordinates	48°44′33″N 25°59′37″E
Length	230 km (140 mi)[1]
Discovery	1966
Geology	gypsum
Website	optymistychna.com/en/

History

The cave complex was discovered by members of the Lviv speleological club "Cyclope" in 1966. It was entirely unknown before then.^[7] There have been more than 50 expeditions since its discovery, 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]

In 2008, the cave was recognized as a Natural Wonder of Ukraine.^[8]

Geology

Speleothems inside Optymistychna Cave.

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 calcite speleothems.^[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

1. This English transliteration was used during the Soviet era but is now deprecated.

See also

• List of longest caves