Small island countries like Vanuatu are experiencing the adverse impacts of climate change, including sea level rise, tropical cyclones, and limited access to freshwater. Vanuatu heavily relies on groundwater as its primary source of freshwater, particularly in Port Vila, the capital. However, the coastal aquifer in Port Vila is facing the issue of saltwater intrusion, indicated by the presence of salinity. To address this problem, a study was conducted to develop and evaluate effective strategies for managing saltwater intrusion in the Tagabe coastal aquifer, which is the major source of freshwater in Port Vila. The study utilized the SEAWAT numerical code to develop a groundwater model, which was calibrated and validated using available secondary data. The model considered different scenarios and incorporated hydraulic barriers such as barrier wells and injection wells to improve saltwater intrusion management strategies. The model also factored in sea level rise and assessed the extent of saltwater intrusion encroachments. The sensitivity analysis based on different scenarios demonstrated that hydraulic barriers effectively managed saltwater intrusion in the Tagabe coastal aquifer. Furthermore, the model accounted for the impact of sea level rise on saltwater intrusion. This study represents the first-ever numerical model developed for Vanuatu, providing valuable insights for water managers, site owners, governing bodies, and stakeholders to develop policies and regulations for managing saltwater intrusion rates in Port Vila. The findings can help prevent contamination of groundwater resources due to saltwater intrusion and serve as a reference for the water industry, private businesses, government agencies, and investors involved in groundwater extraction from the Tagabe coastal aquifer, ensuring sustainable freshwater production rates without the risk of saltwater intrusion.