Lukina jama–Trojama, Cave system in Hajdučki kukovi, Croatia.
Lukina jama-Trojama is a cave system in the Hajdučki kukovi mountains that extends through approximately 3700 meters of limestone passages and descends more than 1400 meters below the entrance. The network features multiple large chambers and vertical shafts that create a complex underground landscape.
Scientists discovered this underground network in 1992 and began intensive geological studies soon after. The findings from these investigations revealed it to be the deepest cave system in Southeast Europe.
The cave system stands as a central point for Croatian speleological research, drawing experts from multiple countries to study its intricate passages.
Access requires official permits and specialized equipment since the cave lies within Northern Velebit National Park. Visitors should be prepared for technically demanding conditions and arrange professional guidance.
The pools inside contain a large colony of leeches, including a species that researchers identified as entirely new to science. This discovery makes the system an important location for studying specialized underground life forms.
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