Sustainably managing the ocean requires reliable measures of the ocean’s contributions to society and the effects that human activities have on the marine environment. This paper informs current international discussions on the measurement of ocean economic activities. It summarises the extent to which the ocean is crucial to society, outlines national approaches to measuring ocean economies, establishes an OECD definition of ocean economic activities for statistical purposes, and introduces a plan to improve international ocean economy statistics through the pragmatic development of satellite accounts. By measuring the full range of ocean economic activities, this framework will improve evidence on ocean sustainability and lay the foundations for ocean accounts that include economic-environmental linkages.