Geospatial data is essential for the development of the blue economy: for sustainable coastal management of coastal areas and to unlock economic potential from marine and ocean resources. In developing countries, such as South Africa, there are often gaps in the data with significant implications for the blue economy. We conducted a project aimed at addressing these data gaps by experimenting with a circular process where geospatial data for selected areas on the South African coastline were collected through mapathons and used in applications that were developed during hackathons. We validated this circular approach with two iterations of mapathons and hackathons, and found that 1) the size and location of the map area need to be carefully chosen; 2) those creating the apps needed a huge amount of help in dealing with the geospatial data; and 3) any geospatial data is useful for the blue economy, not only data with a very specific purpose in the blue economy context, such as coastal access points. Overall, the geospatial data usability improved from one iteration to another and would certainly improve if more iterations were added. Similar to the deployment of mapathons for disaster relief, future research could focus on hosting hackathons for the rapid development of apps to assist with disaster relief operations. Generally, the hosting of mapathons and hackathons in lockstep is a novel way of exposing students to interdisciplinary collaboration in international teams with a common goal.