In all parts of the world the sea is a source of life, of energy, of food, of commerce, of fun. Its water, wind, and waves are all in demand – as a playground for pleasure-seekers and nature-lovers, as a highway for international commerce, as a home for unique communities of wildlife and people. All this is also true for the Bothnian Sea, a part of the northern European Baltic Sea between Finland and Sweden. The Bothnian Sea is used by two neighbouring highly developed societies. There are many demands on its resources, and its open spaces are highly coveted areas for developments such as wind power farms. This relatively sparsely habitated corner of the world is also, at least at times, a place of wild seas and ancient heritage. Like planning on land, maritime spatial planning is a process that has to incorporate ideals of the public good and the various politically-anchored ways to define this, taking in to account private development interests as well as the physical realities of limited natural resources and fragile ecosystems. This book provides an introduction to the Bothnian Sea and the ideas around maritime spatial planning for its offshore areas. We have tried to present a balance between the perspectives of competing interests. As this has been a pilot initiative, we have not aimed to give you ready answers, but instead try to provoke further debate. This book is the summary outcome of the EU funded project Plan Bothnia (MARE 2009/16). The 0,5M euro initiative ran for 18 months between December 2010 and May 2012 under the co-ordination of the Helsinki Commission (HELCOM)secretariat.