Shengsi Archipelago is an island under the jurisdiction of Shengsi County, located in the east of Hangzhou Bay and southeast of the Yangtze River estuary. They are composed of hundreds of islands at the intersection of Qiantang River and the Yangtze River estuary, including more than 404 large and small islands such as Dayangshan, Xiaoyangshan, Shenjiawan Island and Baodaozui Island, among which 16 is inhabited. Sijiaoshan, the largest island, covers an area of 2 1.2 square kilometers.

Shengsi Archipelago is the only national archipelagic scenic spot in China, known as the "Fairy Mountain on the Sea", with original ecological tourism features such as "Bihai Strange Reef, Jinsha Fishing", and more than 50 scenic spots have been identified.