The Chi River (Thai: แม่น้ำชี, rtgs: Maenam Chi, IPA: [mɛ̂ːnáːm tɕʰīː]) is the longest river flowing wholly within Thailand. It is 765 kilometres (475 mi) long but carries less water than the second longest river, the Mun. The name of the river is "Mae Si" ([sīː]) in the Isan and Lao languages of the region, being transliterated as "Chi" in Bangkok-Thai.