The Vrlovka Cave is situated along the Kupa River in a place called Kamanje nearby Ozalj. It was explored in the length of 380 m, 320 m and adapted for tourists. Owing to its natural values and cave decorations, it was protected as a geomorphological nature monument in 1962.
The limestone rocks inside which Vrlovka is situated were formed in a time when this area was covered by the sea, during the Mesozoic era, from shells of very small marine organisms. Later, water drilled its way through rocks as the limestone is soluble in water.
Vrlovka contains a small cave stream, which forms several small lakes. Water together with calcium carbonate from rocks is also responsible for spectacular cave ornaments such as stalactites and stalagmites. The actual length is unknown, but some local stories go so far to tell that the cave extends 5 km all the way to a big underground lake.
Although the complete dark inside the cave seems to be lifeless, life is actually thriving down there – besides many others, it is home for two endemic species, small crab Monolistra velkovrhi and beetle Parapropus sericeus intermedius. It is also home to eight kinds of bats, some of them endangered, so many measures are being taken to protect them.
The Vrlovka Cave has been a source of interest for numerous geologists, speleologists, biospeleologists, paleontologists, and archaeologists. Vladimir Horvat, one of the most prominent Croatian mountaineers, started to set up an access path to the cave. The cave was opened for tourists back on 2 September 1928 after one year of preparatory works. Today, visiting the cave is reduced to only 1 and half months a year due to efforts to protect animal species living inside – this short period is actually the only part of the year when bats have the lowest activity inside the cave.
Ancient settlers of the cave, belonging to Lasinja and Lengyel cultures, left their remains, which have been brought about by archaeological excavations. Vrlovka has also been a place of interest to archaeologists, with the first archaeological excavations taking place even in 1897. It seems that the cave was used as a shelter, but also as a burial ground. Because of the finds of some artifacts that could be used for religious purposes, some theories explain that the cave was used for ritual ceremonies.
One of the most famous finds is a famous bottle from Vrlovka. It is a small vessel, which was attached around hand or neck by string, and according to chemical analyses, it probably contained essential oil and was used for some religious rituals.
Thanks to the latest excavations, the most extensive one undertaken in 2018, on a plateau just above the cave, the prehistoric settlement was found. Because of many finds of lithic material, this place was the center of the production of prehistoric tools. Many finds of loom weights prove developed textile production, as well as bigger fishing weights, point to use of nearby Kupa River as a source of food. Some other finds, like stamp seals or small figurines representing animals, have more hidden still not fully explained purposes.
Like every mystic place, this one also has its own legends. The most famous one is a legend about Dora. According to that story, local villagers were hiding from Ottomans inside the cave, and a young woman named Dora betrayed her fellow villagers by showing the entrance to the cave to the enemy. All the people found inside were taken to be sold into slavery, and Dora, realizing what she has done, threw herself into the river. The partial proof to this story is a wall on its main entrance, built in the 16th century for the protection of local people, but today standing here as a witness of the past times.