Donau-Auen
A green ribbon between two capitals — the last free-flowing Danube in Austria, side-arms and gallery forest saved by the winter occupation of 1984.
The Donau-Auen, declared in 1996, protect the last big free-flowing stretch of the Austrian Danube: thirty-six river-kilometres from Vienna's Freudenau power station to the mouth of the March on the Slovak border, a wooded band rarely four kilometres wide and about ninety-three square kilometres in all — the largest near-intact river floodplain left in Central Europe. The park owes its existence to December 1984, when thousands occupied the Stopfenreuther Au in midwinter to stop a hydropower station planned at Hainburg; police moved in, the country recoiled, and the turbines were never built. The occupation is the founding story of Austrian environmentalism, and the national park is its monument.
The river still behaves like a river here, rising and falling by metres through the year, reworking gravel banks, opening and silting side-arms, feeding water meadows and a gallery forest of willow and white poplar. Some sixty fish species swim the park's waters — more than anywhere else in Austria — among them the huchen, the Danube's great salmonid; kingfishers, the park's emblem, tunnel their nests into raw eroded banks; beavers are back everywhere; white-tailed eagles breed again after half a century's absence; and the warm backwaters of the Lobau and Orth hold Austria's last self-sustaining population of the European pond turtle.
The strangest fact is municipal: the park's upstream end, the Lobau, lies inside Vienna, so the capital keeps genuine floodplain wilderness in its 22nd district — the same river islands where Napoleon staged his army in 1809 between Aspern and Wagram. Downstream, the moated castle of Orth an der Donau houses the schlossORTH visitor centre, its garden island given over to breeding pond turtles.
What's worth knowing before you go
Orth an der Donau is the hub, an easy bus ride from Vienna; the Lobau begins at the tram-and-bike edge of the city, and the Donauradweg cycle path threads the whole park, which is how most people should see it. Guided canoe and boat trips out of Orth and Vienna reach the side-arms that walking never does. Come in May and June for birdsong and fresh leaf, October for colour; snowmelt and summer storms put whole trail sections underwater, and in high summer the mosquitoes are not a joke — cover up at dusk.
The connoisseur's walk is the Stopfenreuther Au itself, below Hainburg: the woods the occupation saved, since re-plumbed by restoration work so that the Danube runs through them again at every high water.