The Cienaga Grande de Santa Marta Ramsar Site (CGSM) is the most important Caribbean estuarine wetland in Colombia. The site represents a strategically important ecosystem supporting the national and local economy. However, their ability to provide ecosystem services has been seriously affected mainly due to changes in land use, disturbances of water flows, man-made climate change and interannual climatic variability. These circumstances led to its inclusion in the Montreux Record, a register of wetland sites on the ‘List of Wetlands of International Importance’ where variations in ecological character have happened, are happening or are likely to happen as an outcome of technological developments, pollution or other human interference. This paper presents the first account of marine and coastal ecosystems developed in Colombia at the Cienaga Grande de Santa Marta. Following the principles for ecosystem accounting of the System of Environmental-Economic Accounting—Ecosystem Accounting (SEEA EA), we developed accounting tables of extent and condition of ecosystems, biophysical and monetary flows of climate regulation and fishing supply and the monetary account of ecosystem assets. Results of the ecosystem account allow visualising the importance of ecosystem services of the wetland, its capacity to provide economic benefits, social welfare and livelihoods at local and national level. Finally, we identify main gaps of information, highlight the applicability of ecosystem accounting to policy- and decision-making on economic and environmental issues and evaluate the challenges to implement it.