Haimen is a district located in Nantong, Jiangsu province, China. Situated on the northern bank of the Yangtze River estuary, the area faces Shanghai across the water. It covers approximately 1,149 square kilometers and had a permanent population of nearly one million residents as of 2025.
The district is known by several titles, including "Gateway to the Yangtze River and the Yellow Sea" and "Little-Pudong." Historically, Haimen was recognized for its salt production and fishing industries. In contemporary times, it has transitioned into a significant port-based industrial hub due to its coastal location along both the Yangtze River and the Yellow Sea.