This article explores the rich marine life in the Sea of Japan, which is an oceanic marginal sea located between the East China Sea and the western Pacific Ocean. It covers a variety of animals, such as fish species (mackerels, sardines, bonitos, salmonids), crustaceans (crabs), molluscs (clams), echinoderms (starfish), jellyfish, sponges, worms, algae, seagrasses, corals, sea turtles, seals, whales and dolphins. Unfortunately there are many threats to this fragile ecosystem due to human activities such as overfishing and pollution. Organizations like WWF have been working with local communities to help protect this unique environment.