The primary objective of this study is to evaluate the land use and natural resources for future sustainable ecotourism site planning using GIS as a tool. The study is based on 2007 land use land cover data and ecotourism suitability data which are then integrated with other GIS datasets to evaluate the land use and natural resources at a district level in Surat Thani province. The final step of this study was the prioritization of the area that is best suited for ecotourism in assessing ecotourism sustainability in Surat Thani province. The result is useful for tourism facilities development and ecotourism resource utilization where ecotourism could be more developed. Additionally, the results can be used for managers and planners working in local and central governments and other non-governmental organizations. These integrated approaches cover complex and universal issues such as sustainable development of ecotourism, biodiversity conservation and protected area management in a tropical and developing country such as Thailand. Moreover, it is believed that this study can be used as a basis for evaluating the suitability of other areas for ecotourism. In addition, it may also serve as a starting point for more complex studies in the future.