This is a photographic guidebook introducing marine planktonic community which consists of a wide variety of organisms travelling marine environments with the current. It contains underwater images showing the natural forms and colors of marine plankters, each of which is indicated with a scientific name and a detailed description. This book covers more than 250 species of marine plankters from many taxonomic groups including jellyfish, comb jelly, heteropod, sea butterfly, sea angel, veliger larvae of gastropods, squids and octopuses, polychaete and peanut worms, shrimp larvae, spiny and slipper lobster larvae, hermit crabs and squat lobsters, Crabs, mantis shrimp larvae, hyperiids, fish and its larvae, rhizarians, and blue-green algae. A larva of giant squid (Architeuthis dux) and some species of radiolarians are photographed for the first time in their living state, of which magnificent beauty could never be observed unless alive. These photographic records are scientifically valuable and meet the needs of researchers. It is doubtless that divers, guides, and researchers will get interested in the book.