Shengsi County is a county in the northeast of Zhejiang province in China consisting of an archipelago of islands located to the east of Hangzhou Bay. It is under the administration of Zhoushan City and is the easternmost county-level division in the province. The islands of Greater and Lesser Yangshan are connected with Shanghai's Pudong New Area by the Donghai Bridge and their port forms part of the Port of Shanghai. They are, however, not counted among the islands of Shanghai.