The territory of Indonesia is dominated by vast oceans. Therefore, Indonesian citizens should be equipped with a deep understanding about sea currents and sea pollution. This study aims to identify the conceptions held by pre-service primary school teachers about both sea currents and sea pollutant migration. The study also aims to identify whether pre-service primary school teachers see a relationship occurring between those conceptions. The study involved 147 pre-service primary school teachers from one of Indonesia's teacher training institutions. Four-tier diagnostic tests were used to gather data about the conceptions of pre-service primary teachers. The data were interpreted and analyzed in a descriptive quantitative method. The results showed that pre-service primary school teachers' conceptions about sea currents and sea pollutant migration were mostly in the category of 'misconception' and 'have no conception'. The correlation test about the ability of pre-service primary school teachers to explain the concepts of sea currents and sea pollutant migration was also not significant. The results of this study indicate a need to improve the quality of teaching and learning for pre-service primary school teachers about convection by linking it to sea currents and sea pollutant migration.