Time brings change. In our fast-moving age, the Earth, and therefore also Nature and our society, are changing ever more rapidly. With high population growth and the progressive diversification of labour, we humans are changing the face of our planet to an unprecedented extent. Some of the greatest challenges result from growing complexity, interconnectedness and linkages across the globe: examples are the increasing integration of international financial markets and the economic interdependence of consumer and producer societies. In a globalized world, comprehending all that happens in politics, the economy and the cultural sphere has become an ever more difficult task. Our scientific knowledge, too, has grown apace. It has become more diverse and multifaceted, creating something of a barrier to understanding and making the lessons to be learned from science less accessible. This applies especially to our oceans. Over recent decades, we have learned, for example, that chemical, biological and physical processes in the marine environment influence each other and cannot be viewed in isolation, requiring a more integrated approach to our interpretation of scientific data and showing that there are no simple answers to the multitude of questions arising in modern marine research. Indeed, as we increasingly recognize that marine ecosystems are worth protecting, many questions and expectations arise. We must begin, therefore, by being mindful of the essentials: by establishing clarity on the concepts and terminology and how to communicate them to a wider public, and being clear about the fundamental principles guiding our actions.