Coastal research deals with that part of the sea, which is significantly affected by the land, and the part of the land, which is significantly affected by the sea. Coasts are in most cases densely populated, and the activities of people are shaping and changing the land/seascape of the coast. Thus, coast encompasses the coastal sea, the coastal land, coastal flora and fauna, and people. Since peoples’ economic and political preferences change and compete, the human impact on the coast changes is contested and subject to societal decision making processes. While some coastal research can help informing and constraining such decisions, many legitimate scientific efforts have little bearing on society. All decision making processes are political, so that scientific knowledge is not the dominant driver in such processes. Using cases from the Institute of Coastal Research of Helmholtz Zentrum Geesthacht, we describe some of these potentially useful parts of science, and discuss under which circumstances the potential usefulness transform into real utility. These cases do not span the full range of coastal science. Important issues are the recognition of alternative knowledge claims, the inevitableness of uncertainties and incompleteness of scientific analysis, the acceptance of the political nature of decisions and the ubiquitous presence of social values. Modesty, self-reflexivity and skepticism are needed on the side of science and an organized exchange with stakeholders and public through designated “border” services.