Cái Nước is a rural district of Cà Mau province in the Mekong Delta region of Vietnam. As of 2019 the district had a population of 136,638. The district capital lies at Cái Nước. The district was split in 2004 to form a new district of Cà Mau province. It previously covered an area of 670 km2 but today covers 395.14 km2.