ABSTRACT Seagrass beds, mangrove forests and coral reefs as a part of marine environments play an important role in the coastal regions. These environments support the coastal communities by providing resources such as food and income. For many years, marine environments have been facing destruction the majority of which is caused by human impact. The lack of knowledge of how to use and manage the marine resources wisely and sustainably is one reason why marine environments are still facing degradation. Primary school children who live in two coastal villages in Lombok Island, Indonesia were questioned about their conceptual understanding of their local marine environments and their ideas about sustainability in these environments. Using an interpretive methodology framework, children and their teachers from Grades 5 and 6 in two primary schools in coastal villages, and elders in the villages were studied and. The data gathered from the children through questionnaires and interviews, and from teachers and elders through interviews. Quantitative and qualitative analysis was used to analyse this data. The children's experiences in their marine environment appear to have strong connection with their knowledge. Their knowledge also developed by interaction with the people in the communities. Children value their local marine environment as a place that provides food for them and their parents teach them to respect it. Long traditions such as dumping waste in the beach or sea has an impact on children from fishing families and creates a contradiction between the positive values they have and negative attitudes they act on. The children are not taught environmental education in the schools since it is not a compulsory subject and teachers lack knowledge about the marine environment. Teachers and elders feel the importance of teaching about the marine environment to their children to give them the knowledge and ability to use the marine resources in sustainable way. For children who are a part of coastal communities, learning about their local marine environment should be made a priority to so they have basic knowledge and understanding in using the marine environment in sustainable ways. Marine environmental education should not only educate children in formal school but also educate people in the communities. The coastal communities as a whole should be working together to achieve the aims of education and conservation. Additionally, the school as a whole needs to support the implementation of marine environmental education.