The Gupo Island is situated northwest of the Baisha Township and southwest of Jibei Island. It is a mesa plateau composed of basalt; extending 1km from north to south, it is the largest uninhabited island among the Penghu Islands. The island is abundant in vesicular basalt, yet its surface is blanketed with ferruginous quartz sandstone, forming a striking contrast. This is truly a unique scene among all islands in Penghu.

Gupo Island houses the British Shipwreck Monument. Its eastern shore is a thriving silver anchovy fishing ground, while the southeastern side features pristine coral reefs, perfect for surfing during low tide. To the north lies the renowned laver harvesting area. Penghu Main Island has many reefs and is exceptionally windy with big waves during the winter, and this place is known far and wide for its abundant harvest of laver. At the end of every lunar year, there will be a significant harvest event, when firecrackers will be lit, and everybody will showcase their best skills to harvest laver, which is a blessing for them in the cold, harsh winter!

The name of the Gupo Island has aroused curiosity and wild guesses. Legend has it that a long, long time ago, a young lady lived in a village who had loved her boyfriend for years. However, her parents were against this relationship and forced her to marry someone else. This frail girl decided to run away from home to fight against her parents’ decision to marry her to someone else and prove her strong love for her lover. She came to an uninhabited island and lived out her days with the sky, the earth, the sea and the mountain as her witnesses. Days passed until she died. When her younger family visited her, they called her "Gupo" (‘great-aunt’ in Chinese) out of respect. When this love story spread out, the lady’s story became the beautiful legend of this desert island!