The Taichung Basin (Chinese: 臺中盆地; pinyin: Táizhōng Péndì), located in the central region of western Taiwan, is the third largest metropolitan area in Taiwan. It occupies parts of Taichung City, Nantou County and Changhua County. The basin borders the Choshui River in the south; the hill lands of Nantou in the east; the Tatu Plateau in the northwest; and the Pakua Plateau in the southwest.[1] A notch connecting the Taichung Basin to the seacoast of Taichung City stretches between the two plateaus.