 Haimen is the seat of the Roman Catholic Diocese of Haimen.Haimen is located in the poorer north Jiangsu region and together with Qidong City, traditionally has one of the highest rates of liver cancer in China and in the world, with upwards of 1 out of every 10 adults in the rural areas dying from liver cancer.The area that is now Haimen was formed from silt deposits from the Yangtze River.