The Lafnitz rises in the Styrian Wechsel region and flows into the Raab after approx. 110 km near St. Gotthard (Hungary). The river is considered one of the oldest borders in Europe. The Lafnitztalradweg B75 runs along the river from its source to the state border. The "Fantastic Tour" is a circular route (39 km) starting in Bad Blumau and also runs along the Lafnitz near Dt. Kaltenbrunn for a stretch.
The course of the Lafnitz has been largely preserved in its original form. This also applies to the Bierbaum/Deutsch Kaltenbrunn area, where the Lafnitz meanders between meadows, fields and forests after the confluence of the Lobenbach south of Burgau until it reaches the Safen river. In the immediate riparian area, floodplain landscapes offer ideal conditions for animals and plants (e.g. brown trout, kingfishers, otters).
The "Lafnitz Valley European nature reserve" comprises two areas protected under nature conservation law: The 70-hectare "Lafnitz-Stögersbach-Auen Nature Reserve" in Wolfau and the 31-hectare "Lahnbach Protected Landscape Area" near Dt. Kaltenbrunn.
The separate parts of the area are connected by the Lafnitz river. The European nature reserve covers a total area of 566.327 ha. The Lafnitz is one of the last unregulated lowland rivers in Austria. The free, unrestricted course of the Lafnitz naturally interacts with the accompanying riparian forests and valley meadows and creates a variety of river morphological habitat structures due to its unrestricted flow dynamics. The area includes the unregulated, largely free-meandering section up to Dt. Kaltenbrunn on the one hand and the "hard" regulated section up to the Austrian-Hungarian border on the other.
The Lafnitz floodplains are freely accessible.