The list of marine cnidarians of South Africa is a list of saltwater species that form a part of the cnidarian (Phylum Cnidaria) fauna of South Africa. This list does not include the freshwater cnidarians. The list follows the SANBI listing on iNaturalist, and does not always agree with WoRMS for distribution. Cnidaria (/nɪˈdɛəriə, naɪ-/) is a phylum under kingdom Animalia containing over 11,000 species of aquatic animals found both in freshwater and marine environments, predominantly the latter.