Dinggouyu is about a kilometer southeast of Jishanyu and is part of Huxi Township. “Dinggou” means “anchor"––the isle looks like a ship’s anchor, hence its name. Dinggouyu is composed entirely of compactly structured columnar basalt, often containing olivine (peridotite) agglomerates. That's because magma flowed in different directions when it rose to the surface. The magma cooled, forming a variety of columnar joints. Weathering and marine erosion ate away at the terrain, creating a unique, varied landscape. Dinggouyu also bears the accolade "Little Guilin on the Sea” because it resembles Guilin, a famous scenic spot in China. Compare pictures of the two places and you'll see why.

Like Jishanyu and Xiaobaishayu, Dinggouyu is a designated Penghu County Columnar Basalt Nature Reserve, safeguarding its distinctive geological formations. Landing on the Dinggouyu is prohibited without authorization; however, the public can book sea cruises to view the island and surrounding isles from a distance. Because there are few traces of humans on Dinggouyu, many protected bird species come here to roost and breed from April to September, including summer migratory birds such as white-browed terns, red terns, and black terns. It’s a must-see for birdwatchers!

Every winter, from November to January, the reefs along Dinggou Island are rich with natural "black gold" laver, an edible seaweed. During the Qing dynasty, the villages of Huxi, Hudong, Baikeng, and Beiliao took turns collecting laver here. The seaweed harvest is a collective local industry. Nonresidents are forbidden to land or pick seaweed on Dinggouy without permission!