The Xihu Trough is a region in the East China Sea, located approximately 400 kilometres east of the cities of Shanghai and Ningbo, Zhejiang. The region is a repository for natural gas, and consists of the Chunxiao, Tianwaitian, Canxue, Duanqiao, and Pinghue fields. The entire trough is approximately 500 kilometres long, and runs parallel to the Chinese coast.