Seafarming is a growing economic activity in Indonesian coastal areas. The level of investment required for this activity is lower than in the capture fisheries and in the agricultural industry. However, in considering the development of seafarming activities one not only needs to take into account direct economic benefits, but also social and environmental spillovers with a view to approaching a more sustainable degree of economic development. After outlining the economic significance, development and adverse environmental effects of seafarming activities in Indonesia, this paper examines the economics and socio-economic benefits of seafarming taking seaweed culture as a case. It is estimated that the potential economic return from seaweed farming appears to be high in Indonesia as can be best judged from the internal rate of return figure which is estimated to be 47 per cent. The paper also considers the socio-economic prospects for giant clam farming in Indonesia. It reviews the current status and utilisation of giant clams, examines the environmental advantageous of clam farming and considers the market and possible socioeconomic benefits of clam culture.