This study aimed to assess ecotourism in a mangrove area and whether it conformed with sustainable tourism. We were interested in exploring the demand for natural resources and the supply of areas for ecotourism. To achieve this, we integrated a SWOT (strengths, weaknesses, opportunities, and threats) analysis with the DPSIR (driving forces, pressures, states, impacts, and responses) framework, based on questionnaire interviews with three target groups (tourists, homestay operators, and community residents), plus in-depth interviews with local scholars and officers of administrative organizations. Supplementary data recorded included the physical characteristics of local homestays and houses. The results were analyzed statistically and the ecotourism carrying capacity of the area was assessed, based on the SWOT analysis. Internal factors included key strengths, e.g., the income associated with nature-supporting tourism, and key weaknesses, e.g., local stakeholders' awareness and understanding of ecological mechanisms. External factors included opportunities arising from tourism policies and public relations and threats from town and urban planning and pollution from nearby areas. The DPSIR framework was used to rank the scores of each DPSIR dimension, with the responses identifying DPSIR indicators prioritized. Finally, a conceptual DPSIR model of ecotourism, which illustrated the ecotourism lifecycle, was developed.