Tongpan Island is located in the southwest of Magong Port. Surrounded by basalt columns, the columnar joints are jagged, especially the magnificent and steep cliff coast, the beautiful scenery is natural, and it has the reputation of Penghu Yellowstone Park. The whole island is surrounded by vertical columnar basalt, except for the bay where the fishing port is located in the north. Originally, the columnar joints of these stone pillar groups were very clear, in the shape of five or six angles. The basalt at the top of the cliff has been subjected to severe weathering and erosion for many years, causing the edges and corners of the rock pillars to gradually disappear, or into spherical or independent stone pillars, with various shapes and changes, which has become the unique basalt weathering feature of this island.