Tutong District is one of the four districts of Brunei. The main town is Tutong. The district borders the South China Sea to the north, the Bruneian district of Brunei-Muara and the Malaysian state of Sarawak to the east and the Bruneian district of Belait to the west. The Tutong River flows through the district. With the size of 1,166 square kilometres, Tutong District is the third largest district in the country. As of 2016, it has the population of 49,438 and comprises five main ethnic communities: Tutong, Dusun, Kedayan, Iban and Chinese.