Tardigrade diversity is measured by the richness of species in a given area. Little is known about the diversity of marine tardigrades and only nine of 38 North American marine species have been documented along the Pacific coast. Recently, six species or subspecies were collected and identified from Santa Cruz Island. Only one, Echiniscoides sigismundi sigismundi, was previously known from the area. Echiniscoides sigismndi groenlandicus, Echiiscoides hoepneri, Antechiniscus marci, Batillipes dicrocercus, and Wingstrandarctus intermedius are new records for the Pacific coast of North America. This increases the known marine tardigrade diversity from 9 to 14 species. With these new finds, the statistical estimate of species richness along the California coast has grown to about 24, leading to the conclusion that many additional species will be found.