The nature reserve Slepičí Vršek (Hen Mound) lies about 6 km north of the town Třeboň.
The reserve is 1.8 ha large. There is a protected sand dune, one of two drifted sand dunes in South Bohemia (the other is Vlkovský Přesyp - Vlkov Sand Dune). It was formed by wind on sand silted by the Lužnice river along its flow.
The sand dune can be found on the field path, which leads from the small village Lužnice (about 1 km).