Ocean literacy is an understanding of the ocean's influence on us and our influence on the ocean. A lack of ocean literacy presents a significant obstacle for citizens to engage in environmentally sustainable behaviour, and thus is acknowledged as a 'complex problem' that requires deliberative participation and joint-action by stakeholders across domains. The aim of the article is both to demonstrate the value of Collective Intelligence (CI) as a methodological tool to advance and enhance the promotion of environmental literacy, and to share outcomes from using the CI approach. The participatory context behind CI illustrates that working 'with' a range of stakeholders across marine education, outreach, regulation and policy, to debate how to better promote ocean literacy among young people, improves ocean literacy and broadens society's awareness of sustainable marine environments. Findings reveal a hierarchical barrier structure localised to each country, a valuable order of echelon toward environmental change.