Economic activities in marine based coastal areas, aim at improving community welfare, this article discusses the existence and development of marine based economic activities in penjaringan district, North Jakarta. using a rapid appraisal approach an deep interviews, data on economic activities were gathered. the results show that there are four marine-based coastal economic activities in penjaringan district, namely fishing , green mussel cultivation, fish processing industry , and holticulture. fishing was operated in kepulauan seribu, pulau bawean, gresik, Pulau Bangka belitung, and south china osean , fish processing industry includes dried fish. the four economic activities are financially feasible to be more developed. however, concerning health and ecology aspects, green mussel cultivation is not recommended since the mussel contains poisonous heavy metal contaminant.