The Norwegian coastal current originates primarily from the freshwater outflow from the Baltic and the freshwater runoff from Norway. It flows northwards along the coast of Norway as a low-salinity current. This coastal region is the spawning ground for a number of important oceanic fish stocks, and the physical environment has an impact on the recruitment, growth, and geographical distribution of these stocks. In the late 1920s and early 1930s, the Institute of Marine Research in Norway established a coastal oceanographic observation system. This continued to evolve, and its core elements are still in operation. Drawing on the results generated by this observation system, as well as by other coastal studies, this book reviews the current understanding of the physical/chemical conditions in the Norwegian coastal current in such a way as to make the material more easily accessible to non-specialists. A series of chapters introduces readers to the geography, currents, water masses, and the temporal and spatial variability of the Norwegian coastal current. Interannual fluctuations in physical conditions are most likely to be the prime cause of ecosystem variability. The editor hopes that this book will act as a point of departure for a future summary of the ecology of Norwegian coastal waters.