The National Park is 38 kilometres long and no more than 4 kilometres wide. It stretches from Vienna right up to the point where the Danube leaves Austria at the border at Hainburg and flows into Slovakia. 65% of the area is pasture land covered with forests, 20% of it comprises lakes and streams, and only 15% contains cultivated fields, meadows and other types of land. The forests are home to more than 700 species of taller vegetation, 30 types of mammal and 100 varieties of breeding bird, 8 species of reptile and 13 amphibians, as well as around 60 types of fish.
At the end of the 19th century man began to alter the ecological balance of the countryside along the shores of the Danube by constructing river controls and, in the 1950s, with the construction of hydro-electric power stations. Finally, in 1984, plans to construct a power station at Hainburg threatened to put an end to the last remaining free-flowing stretch of the Danube and conservationists created a furore with their now legendary call to the public to take possession of the meadows in a squat. When the authorities concluded legal proceedings on 5 December 1984 construction work began at Stopfenreuth. On 8 December 1984 an initiative organised by the Austrian Students' Union saw protesters march from every part of the country to the meadows. Thousands of people of all ages and walks of life then took over the meadows in a squat and resisted every effort to remove them, with the result that the felling and clearing operations had to be abandoned. In December the government decreed that the clearing operations be officially halted and ordered new scientific investigations to be carried out. The findings concluded that the area was of such great conservation value that it ought to be made a national park and that a power station should hence not be built there. On 27 October 1996 the Austrian national government and the governments of the states of Vienna and Lower Austria signed an agreement establishing the national park. The Hainburg meadow protestors had won a famous victory!
The stamp depicts the poster by the master painter Friedensreich Hundertwasser who was himself one of the Hainburg squatters and a campaigner for the preservation of unspoilt nature.