In this book, 95 scientists report on their research in the ocean and along the coasts. They take the reader from the ice-covered polar seas through the North and Baltic Seas to seagrass meadows, tropical mangroves, and coral reefs. The contributions illustrate the diversity of communities between the beach and the deep sea. The size spectrum of organisms ranges from whales and fish to planktonic crustaceans and mollusks, down to diatoms and bacteria. The global biogeochemical cycles driven by marine life are discussed, as well as the molecular biological adaptations of microorganisms, where the greatest methodological advances are also noted. Exciting topics in applied marine research include overfishing and the sustainable use of the oceans, as well as threats from pollutants and nutrient inputs.