The Southwest Coast National Scenic Area is a special national-level scenic area located in the Chianan Plain. Its geographical scope covers three counties/cities and a total of eight coastal townships/districts, including Sihu and Kouhu (Yunlin), Dongshi and Budai (Chiayi), and Beimen, Jiangjun, Qigu, and Annan (Tainan).
- Northern boundary: Yunlin County’s Old Huwei River (including the townships of Sihu and Kouhu [Yunlin] and Dongshi and Budai [Chiayi]).
- Southern boundary: Tainan City’s Yanshui River (including the districts of Beimen, Jiangjun, Qigu, and Annan [Tainan]).
- Eastern boundary: Provincial Highway No. 17 (not including Tainan Technology Industrial Park, but including the dormitory complex of the former South Japan Salt Industry Co. Ltd. located in Budai Township, Chiayi County, and the Nankunshen Special District Planning Project located in Beimen District, Tainan City).
- Western boundary: The 20-meter bathymetric contour (not including the water to the north of Waisanding Barrier Island).
- Total area: Approximately 87,802 hectares (land area: 37,166 hectares; water area: 50,636 hectares).