Sea vegetables are edible marine algae harvested from the ocean; the term overlaps heavily with "seaweed" but is sometimes used more broadly to include other edible coastal plants such as sea beans.
Common types include nori, kombu, wakame, dulse, and hijiki, each with a distinct texture, color, and flavor. Nori is toasted and used to wrap sushi rolls or eaten as a snack; kombu is simmered to make dashi; wakame goes into miso soup and seaweed salads; dulse is eaten raw or added for a smoky note; hijiki is simmered with vegetables and seasoned with soy sauce and mirin.
Sea vegetables have been a dietary staple in Japanese, Chinese, and Korean cooking for centuries and are now widely used elsewhere in salads, soups, and snacks.