The Vietnamese Mekong Delta is under great threats of climate change and sea level rise. In order to sustain the development of the area, an appropriate decision support approach should be developed, in which the natural resources and socio-economic dynamics are interactively considered. Such the approach should be able to: (i) support the participation of different relevant stakeholders in the society; (ii) support multi-scales and multi-disciplinary analysis; (iii) consider both spatial and temporal dimensions; and, (iv) help raise capacity of relevant stakeholders. In this paper, we present an example of the application of an interactive approach in the case study of Bac Lieu, a coastal province of the Vietnamese Mekong Delta, with the main focus on visualization to call for attention and sufficient contribution from local farmers, local and provincial governmental staffs, and national and international scientists. A decision support system was developed to help local and provincial government project changes under impacts of different climate change scenarios and institutional arrangements. In this approach, GIS plays an important role in visualization of the derived information to support decision-making.