In this study, the Wadden Sea, as an out-of-school learning site, is considered from an empirical-research perspective of environmental education. The Wadden Sea in Germany is part of the largest contiguous mudflat area in the world. Although much evidence is already available on different teaching and learning processes at various out-of-school learning sites, this is not yet the case for the Wadden Sea. This research gap was taken up. In this paper, 427 students (mean age: 11.74 years) participated in a mudflat hiking tour. A pre-post-test design followed by a retention test was used to determine the impact of this on participants' environmental attitudes and environmental knowledge. The single factor analyses of variance with repeated measures demonstrated that the mudflat hiking tour had both a positive short-term and a positive long-term impact on environmental attitudes, as well as on environmental knowledge. All three constructs could, therefore, be positively influenced by the intervention. Correlation analyses revealed a positive relationship between environmental attitudes and environmental knowledge at three measurement time points. These results empirically confirm the potential of the Wadden Sea as an out-of-school learning site for environmental education with students from secondary schools. The effectiveness of non-formal education in this ecological environment can be proven.
Keywords: UNESCO World Heritage Site; Wadden Sea; environmental attitudes; environmental education; environmental knowledge; out-of-school learning.