This dataset contains student responses to pre- and post-intervention surveys designed to evaluate ocean literacy levels and assess the impact of an educational intervention. Three classes from different grade levels participated. The questionnaires were slightly adapted between pre- and post-intervention stages and across primary and secondary education levels. The survey design was based on ocean literacy dimensions and the Ocean Literacy and Mediterranean Sea principles. As the intervention focused on a specific coastal marine area (Elounda bay, Crete) selected questions addressed topics relevant to the local marine environment.