The Radomka is a river in central Poland and a left tributary of the Vistula. It has a length of 98 km and a basin area of over 2000 km² (all in Poland). The river has its source in forests 4 km south from Przysucha, at the height of 310 meters above sea level. There is a retention reservoir, built in the valley of the Radomka in Domaniów, which has the largest surface area of any lakes in Mazowsze Voivodeship (5 – 7 km²). It is also utilised for recreation purposes.
After flowing through the hills of the Lesser Poland Upland, the Radomka enters a wide urstromtal, to finally enter the Vistula near Ryczywol, at the height of 160 meters above sea level.
The reserve, located in a forest at the source of the Radomka, was opened in 1978. Its purpose is to preserve natural wilderness, with its fir and beech trees.
Coordinates: 51°42′31″N 21°26′07″E / 51.7087°N 21.4353°E