？verda – Speleological Explorations of the Rje？ina Spring Hinterland

Sa？etak ？verda is well-known among the speleologists as a mountainous karst area located at the northwestern-most part of Gorski kotar county. The area stretches along the Slovenian–Croatian border in between the Sne？nik and Risnjak mountains and for the most part, its elevation is above 1000 m a.s.l. It is one of the areas in Croatia with the greatest average annual rainfall and lowest average annual air temperature. The terrain is highly karstified, which is evident by multiple surface and underground karst forms. Caves are characterized by vertical morphologies and are often filled with snow and ice during most of the year. This area constitutes a drainage basin for some of the most abundant springs in the northern Adriatic — Rje？ina, Zvir and Kupa springs — by which it bears a role of strategic importance for long-term water supply. Systematic speleological explorations were not conducted until recent, while publications covering this area are very rare. Caving society ？Estavela“ began systematic speleological exploration of ？verda in 2005. Over the following 13 years, 10 speleological expeditions were organized with more than 150 participants from 19 speleological organizations, often from abroad. 156 caves were explored, among which three of those are on the list of the 55 deepest caves in Croatia. The deepest cave is 310 m deep, but the depth-potential of the area has not been reached considering that across the border there is more than 600 m deep cave where exploration is still ongoing. The primary goal of this publication is the presentation of the natural characteristics of this area and collection of all the results of speleological explorations achieved so far. The area is presented geographically, climatologically, geologically, hydrologically, glaciologically, and with descriptions of the flora. An historical review of speleological explorations, explorations in Slovenia near Sne？nik mountain, and the results of biospeleological research are also given. The core of the publication is cave cadastre, where every cave is presented by basic data, vectorized map, and photography of the entrance