Karst sinkhole and cave in Karajimiškio village (Biržai district), Biržai regional park. This is the best-known and best studied geological natural monument in Northern Lithuania. Monument published in 1964.

Cavers believes that it - about 200 years. It has a diameter of 10-12 meters, depth - 12.6 m. Bottom of the pit is open hole. Cave walls overlooking the Upper Devonian rocks - dolomite, gypsum, marl. 9 m deep karst subsidence at the bottom of the 5 branches (wet cave, Narrow canal, canal bats, frogs Cave) and 1.5 m deep underground lakes.

One hole goes to the north-east, two in the southeast. The total length of the aisle 46 years, the threshing floor area of ​​42 sq meters, the volume of 28 cubic meters. Groundwater lake water temperature is 4.5 ° C. The lake found in nine-and three-spined stickleback and shellfish, one Lando found bats (whiskered bat, northern bat and brown long-eared bat) skeleton.

1973-1978 m. Cave studied Kaunas cavers. 1978. Immersing examined the underwater part of an underground lake. Cows Ola still actively developing. These parameters length caves, sinkholes form other voids changing.

2007. Lithuanian caving club Aenigma and Russian divers - cavers carried out research in flooded parts of the cave. It has been discovered yet unknown submerged caverns.