Cimei Island is located 119°40' East and 23°16' North. It is approximately 29 nautical miles (36km) from Magong, 48 nautical miles west of Tainan and 58 nautical miles north of Kaohsiung. The island has a total surface area of 6.99km2 and a perimeter 14.4km long. It is table island and has the fifth largest surface area among the Penghu islands.