The fact that oceans and seas matter for sustainable development is undeniable. Oceans and seas cover over two thirds of the earth's surface, provide food and minerals, generate oxygen, absorb greenhouse gases and keep in check climate change, determine weather patterns and temperatures, and serve as highways for sea-borne international trade. The oceans economy is one that seeks to promote economic growth, environmental sustainability, social inclusion, and preservation of livelihoods. At its core it refers to the de-coupling of socio-economic development of oceanic activities from environmental and ecosystems degradation. The Oceans Economy: opportunities and challenges for Small Island Development States (SIDS) report is the consequence of a joint effort from a team of experts from UNCTAD and the Commonwealth Secretariat to better understand the implications of the nascent and evolving concept of the oceans economy. This report underlines the importance of sustainable oceanic activities for the development of SIDS and other coastal states.