The Kolok River (Thai: แม่น้ำโกลก, RTGS: Maenam Kolok, Thai pronunciation: [mɛ̂ːnáːm koːlók]; Malay: Sungai Golok) is the boundary river between Narathiwat Province, Thailand and Kelantan, Malaysia at the Malay Peninsula. The river flows into the Gulf of Thailand at Tak Bai district, Narathiwat Province.
The river originates in mountainous area of Waeng district then flow through Su-ngai Kolok and Tak Bai districts. It is 103 km long.