Caofeidian District, formerly Tanghai County, is a district of Tangshan, Hebei, People's Republic of China, along the coast of the Bohai Sea. As of 2003, it had a population of 140,000 residing in an area of 725 km² (280 sq mi). The district's administration is highly unusual in that apart from its seat, Tanghai (唐海镇) and two other towns Binhai (滨海镇) and Liuzan (柳赞镇) the rest of its administrative units are informal, mostly being farms.