Nature Park Radensko Polje is located in the southeastern part of the Grosuplje municipality and is an exceptional karst field in size of about 4 square kilometres. It features a variety of typical karst phenomena, forming a natural mosaic of meadows, shrublands, forests, and intermittent lakes. The park also has a raised forested perimeter, guarding the secrets of this extraordinary natural jewel. The notable karst features include
- pronounced ‘retije’/estavelles (Novljanovo, Veliko retje, Srednjice),
- karst sinking caves (Zatočna jama),
- occasional ‘ponor’ caves (Beznica, Lazarjeva jama, jama Pekel),
- dry karst caves (Viršnica),
- numerous smaller sinkholes and dolines,
- as well as permanent (Šica) and occasional karst springs (Zelenka).
Additionally, this area, with its mix of dry and wet meadows, floodplain forests, peat bog remnants, and diverse aquatic and riparian vegetation, is a crucial biodiversity hotspot.
The Dobravka River flows into the area from the non-karstic world, characterised by a narrow, steep channel in clay deposits, especially prominent under the Boštanj hill. There, near Veliko Retje, significant sinkholes and estavelles through which water drains underground during low water levels are visible. In rainy periods, the process reverses, with water emerging from holes at the bottom. Under normal water levels, the Dobravka disappears into the Beznica Cave.
The Zelenka Stream, originating near the Pirka hamlet, is typically karstic with a funnel-shaped karst spring and a karst sinkhole in the Pekel Cave. Its bed is mostly dry, filling only during prolonged rainfall.
The Šica River, the most well-preserved river, springs in the southwestern part of Radensko Polje near Mala Račna village. It meanders significantly, making a triple-length journey to its sinkhole in Zatočna Cave. During high water levels, the southern part of Radensko Polje is inundated by Zelenka and Dobravka, with waters also flowing into the usually dry Lazarjeva Cave.
All three watercourses flow from west to east, where they disappear and reappear as part of the Krka River’s source.
