| Cát Hải district | |
| Native Name: | Huyện Cát Hải |
| Settlement Type: | District |
| Pushpin Map: | Vietnam |
| Pushpin Map Caption: | Location of Cát Hải in Vietnam |
| Subdivision Type: | Country |
| Subdivision Type1: | Municipality |
| Subdivision Name1: | Haiphong |
| Seat Type: | Capital |
| Seat: | Cát Bà |
| Area Total Km2: | 345.31 |
| Population As Of: | 2019 |
| Population Total: | 32,090 |
| Population Density Km2: | auto |
Cát Hải is a rural district (huyện) of Hai Phong, the third largest city of Vietnam. It includes the old Cát Bà town since 1977.[1]
As of 2018 the district had a population of 43,187. The districts covers an area of 295km2. The district capital lies at .[2]
The island is subject to major land developments. Vinfast is building an automobile factory on the southern half of the island,[3] and Sun Group is developing a holiday resort on the northern half. A 5.44 km long bridge - the longest sea crossing in Vietnam - connects the island to Hai Phong.