Dzierzno Duze is a large artificial reservoir located in Upper Silesia, near Gliwice. It is an important kitesurfing spot for riders from the Silesian agglomeration (Katowice, Gliwice, Zabrze). The water body is vast (approximately 6 km squared) with good sailing distances. The depth is moderate and the bottom sandy. In strong winds, the fetch creates significant chop. The lake works with winds from most directions. West and southwest winds are the most frequent. It is an accessible spot from the A4 motorway and very popular on weekends with Silesian riders.