Coastal phytoplankton exhibits an incredible diversity of life forms. It is not uncommon to find 40 or 50 different species in just a few drops of water. In this photographic guide to the North Sea, we describe the main phytoplankton groups, diatoms, and dinoflagellates, with additional information on ciliates and smaller flagellates. Overall, we provide taxonomic, ecological, and biogeographical information on more than 130 taxa. Since the majority of students and professional plankton analysts primarily work with light microscopes, the species in the book are documented with light micrographs that offer the reader a realistic view of the species in a water sample. Therefore, the book is suitable not only for students and environmental managers but also for amateur microscopists and enthusiasts. Dr. Alexandra Kraberg has been working with phytoplankton for over 12 years.