Pazin Cave or the abyss of Pazinčica, the largest Istrian river abyss, is located in central Istria, and above it was built the famous Pazin castle. In the hydrogeological sense, the pit represents an abyss created by the contact of the watertight flysch base of the Pazinčica basin and the watertight limestones that make up the entire area of southwestern Istria. Once upon a time, Pazinčica flowed on the surface of the earth, passing by Berm and Dvigrad all the way to the sea, forming the Lim bay.
The Pazin abyss is protected by law and declared an important landscape, and includes the canyon and abyss of Pazinčica, about 500 meters long and about 100 meters deep, and of course the Pazin pit whose length of the underground part is 287 meters. The first speleological research began in the late 19th century, when the French speleologist Eduard Alfred Martel carried out the first draft, and then in the 1960s Mirko Malez made a new draft with a detailed geological description.
The first speleological diving research was conducted by the Istria Speleological Society in 1975, which was repeated in 2015, and Antonio Ciceran from the Had Speleo Club made a new detailed draft.
The entrance to the Pazin Cave is located below the almost 100 meter high vertical rock on which the houses of the town of Pazin are today, and the entrance is through a high and wide semicircular vaulted cavity. The underground canal extends further in a southeasterly direction, narrowing and widening and eventually forming a long and wide end hall with a siphon lake also known as Martel Lake. It is connected by a siphon with the next one, Mitrovica Lake, in nature by a water canal that ends with a waterfall and a new siphon with an unexplored extension.
The unusual play of nature also inspired the novelist Jules Verne to take his heroes through the mysterious Pazin Cave with his imagination in the novel Mathias Sandorf, but it also inspired other writers such as Nazor or Dante.