Kuala Sempang is a coastal village in the Bintan Regency which has the largest mangrove ecosystem. This village’s advantageous location near the estuary of the Busung River gives it the opportunity to develop marine-based ecotourism. Unfortunately, this untapped potential has not yet been fully realized. Consequently, the purpose of this study is to propose a planning concept for the development of sustainable marine-based ecotourism in Kuala Sempang. This study employs both qualitative and quantitative methodologies, including interviews and observations, as well as visual analysis utilizing drone imagery and Google Earth. This study intends to generate a spatial and architectural design for potentially developable areas. In addition, a gross budget estimation plan (RAB Global) will also be produced, explaining the total amount will be spent on the development of each area. According to the findings, three seven locations have a good chance of becoming ecotourism destinations: Dapur Arang Sei Lepan, the coastal area of Busung Bridge, and the area surrounding Empat Islands. According to the RAB Global, a multi-years village fund would not be sufficient to cover the full expense of developing the area. Government assistance and private investment are also required for the development of these potential marine tourism destinations.