Two master students at the École Polytechnique Fédérale de Lausanne (EPFL) were asked to produce an énoncé théorique: theoretical research, exploring a subject that they deemed interesting and relevant to introduce their diploma project. They chose to study the Baltic Sea through a selection of various climatical, geological, social and political topics. This book is the result of those four months of research. The énoncé théorique goes into detail—through maps, diagrams, charts, etc.—searching for clues and patterns on what an overexploited territory looks like (different layers of interaction) and what planning such a territory would imply. This book hopes to generate more ideas on how the exploitation of the Baltic Sea could be organised so humans can adequately manage and use the resources offered by the sea, today and in the future. Planning will become crucial for the Baltic Sea where user pressures are currently relatively manageable but are expected to witness a strong shift in the years to come. (Muriz Djurdjevic, Thomas Paturet)