Su'ao Harbor, located at Su'ao Tonwship, Yilan County, was called ''Donggang'' in the past. It is an outstanding natural harbor surrounded by Beifangao, Su'ao, and Nanfangao on three sides. Many people come fishing here. The government built a small commercial harbor at Su'ao Harbor in 1965. It was enlarged into an international commercial harbor in 1974. The harbor was broad and full of reefs. The sea reflects the blue sky and the figures of ships. It is one of eight Lanyang scenery spots, ''Su'ao Mirage.'' The best locations for appreciating the harbor are Battery Mountain and Sunan Highway. On both sides of Su'ao Harbor are Nanfangao Harbor and Beifangao Harbor.