The assessment of visitor understanding and perceptions of natural landscapes and attitudes towards functions of a river national park is important for the acceptance and success of park management. The study asked 426 visitors to the Donau-Auen (Danube Floodplains) National Park in Eastern Austria about their affinity to the national park brand, their understanding of the river landscapes and attitudes towards the functions of a national park, and to what extent the visitors perceive the Danube Floodplains as a national park at all. The results show that a large proportion of respondents have some understanding of river national parks and their functions. Many respondents have a sense of being in a national park. However, for 60% of the respondents, the national park brand played almost no role in a visit to the national park. Visitors who have a higher affinity for the national park showed a stronger agreement with the functions of a national park. Those images from the Danube Floodplains National Park that depicted natural landscapes were judged by the majority of respondents to be typical of a river national park, but also meadows. Differences regarding the national park landscapes were not found among visitor affinity segments. Implications for environmental communication are presented.