Established in 1996, the Donau-Auen National Park covers around 9300 hectares and runs in a thin strip on both sides of the Danube, extending from the edge of Vienna to the Slovakian border. About 60% is forested and approximately 25% comprises lakes and waterways. The park was created to protect an environment threatened by a hydroelectric power station in Hainburg. You’ll find plentiful flora and fauna, including 700 species of fern and flowering plants, and a high density of kingfishers (feeding off the 50 species of fish found in the waterways here). A Nationalparkhaus (National Park Office) is situated on the northern entrance to the park and offers a series of tours – see the website and register in advance; some are free, others cost for adults/children about €10/5. Boat tours into the national park leave from Salztorbrücke and last 4½ hours; booking necessary.