The North Kent Marshes are in the far north of the county of Kent spanning dry and wet south banks and inlets of the Thames Estuary in south-east England. The marshes are one of 22 Environmentally Sensitive Areas recognised by the UK's Department for Environment, Food and Rural Affairs (DEFRA). They are in the Thames Gateway regional planning area. They include the 5,289-hectare (20.4 sq mi) South Thames Estuary and Marshes biological SSSI.