Differently from Velebit, the caves in Istra have already been „explored“, but that does not mean they are not interesting. Istrian caves are warm, with a lot of decorations and rather demanding, so it is good to have an experienced guide when one starts to explore Istrian caves and pits.
Underground halls, lakes, creeks, gorges, vertical pits, cracks and fossils will delight every visitor. In Istrian caves and pit beside natural beauties there are also very diverse animals and plants (fish, frogs, doormice, little crabs, blind mice), and the most interesting is the “human fish”, Proteus anguinus, an endemic species living only in this karstic areas.
Te cave of Pazin has become world famous, as it has been celebrated by Jules Verne describing it in his novel „Mathias Sandorf“. Until now, about 1500 caves are known, and every year about ten new ones are discovered. Ćićarija in the north of Istra is a separate karstic entirety where the deepest cave of Istra is situated, the abyss Rašpor, 361 meter deep.
Near the small town of Roč there are the abysses Krkuž and Gragorinčići. The longest cave in flish is Piskovica in the central part of the peninsula, 1036 meters long. In the vicinity is also the 273 meter deep Marfanska pit consisting of 2045 meters of explored canals and is also the longest one in Istra. The largest hall adorns the Batluška pit, 200 meters long and 150 wide and 60 meters high.
The north-western parts are special by a row of abysses in the contact area of flish sediments and limestone. A very picturesque abyss near Šterna is 231 meter deep, and it is especially beautiful in the rain period when at the bottom of the pit a waterfall is created, and before disappearing in the deep of the earth, it makes a small lake. There is also an abandoned old mill nearby.
The karstic area of western Istria is very interesting as it is covered with red earth so dripstone and crystal underground are often expressively red coloured. Beside pits, caves are also very interesting speleological sites. For their accessibility, the staying f men and animals in them goes very far back into the past, so that many of them are today interesting archaeological and paleontological finding sites: Šandalja, Vergotinova, Romualdova, Trogrla… are only some of them.