Located in the southern tip of the PenghuFong-GueiIsland, Fong-GueiCave is one of the well-known attractions in Penghu which visitors should not miss. It is used to be known as the "Fong-Guei Tail". Here, because the unique basalt columnar joints in Penghu are highly developed, and are long-term eroded by the ocean waves, there formed a narrow ocean-erosion ditch.