Su-ngai Kolok is a border town and subdistrict on the Malaysia-Thailand Border in Su-ngai Kolok District, Narathiwat Province, Thailand. It is …Su-ngai Kolok is a border town and subdistrict on the Malaysia-Thailand Border in Su-ngai Kolok District, Narathiwat Province, Thailand. It is one of the largest and most prosperous districts in Narathiwat Province. It is also one of the major economic centers in the southern part of Thailand. It is the capital of the Su-ngai Kolok District. As of 2005, the town had a population of 38,612. Across the border is Rantau Panjang, Kelantan, Malaysia.