Natural settings
The cave was formed in the Mesozoic Middle Triassic dark grey limestones of the Choč Nappe with chert intercalations. There are also positions of altering pale-grey dolomites. The direction of cave passages is significantly predisposed by steep tectonic faults.
The cave reaches the length of more than 3,000 m with vertical span of 95 m. It was formed by the ponor waters of Bystrianka flowing into the karst territory from the southern slopes of the Low Tatras Mountains in several developmental stages in dependence to the valley bottom deepening. Meander riverbed in the Old Cave is the oldest part of the cave, with an entrance situated 70 m above the present flow of Bystrianka. At present, the ponor watercourse is flowing through the lowest and youngest parts of the New Cave, which are situated 14 m lower than the 160 m distant ponor of Bystrianka in front of the cave. The water course appears also on the bottom of the nearby Bystriansky Doline, which has abyss spaces more than 650 m long and 165 m deep. The springs in Valaská are 3,300 m away from ponors with elevation difference of more than 70 m.
The main spaces of the New Cave have narrow and high fissure passages widened by corrosion and erosion of the water course. Shorter oval passages are prevailingly predisposed by interbed surfaces and they connect the narrow fissure passages in some places. The upper parts of tectonic faults are widened by corrosion of percolating atmospheric waters in several places. Also larger halls and domes are present, mostly of breakdown character (Collapsed Dome, Mostárenské Halls). The Hell Abyss 56 m deep opens into the lower parts of the New Cave.
Flowstone fill is dominated by curtains (Chapel), which sometimes hang from the edge of flowstone crusts formed on previous and later washed out river sediments (Baldachin). Aragonite occurs in places under the Hell.
Air temperature is from 5,7 to 6,7 °C, relative humidity 92 to 98 %. Eight bat species were determined in the cave with the most abundant Lesser Horseshoe Bat (Rhinolophus hipposideros) and Greater Mouse-Eared Bat (Myotis myotis).