Recent research in Ireland has estimated both the national and regional economic value of the marine sector. However, economic activity does not exist in a vacuum. Activities in the marine sector not only directly affect the industries in the sector but also influence other sectors through inter-sectoral linkages. This paper uses an Input-Output (IO) methodology to examine the linkages and production effects of the Irish marine sector on the national economy. Disaggregating the Irish IO table for 2007 to include ten additional marine sectors, this paper represents the first effort to quantify the inter-industry linkage effects, production-inducing effects and employment multipliers in the marine sector. This analysis found that a number of marine sectors, notably the maritime transportation sector, have an important economic role within the wider Irish economy.