Ko Mak (Thai: เกาะหมาก, pronounced [kɔ̀ʔ màːk]) is a small island of Trat province, Thailand.

The first settler on the island was Chao Sua Seng, a Chinese Affairs Officer during the reign of King Rama V, who established a coconut plantation.

Luang Prompakdii and his children are known to have established more coconut and rubber plantations, effectively covering most of the arable land in these two sought-after exports.

[1] The first attempt at attracting a tourism market was in 1974, when bungalows were built at Ban Ao Nid on the east of the island.

Infrastructure, specifically transport and telecommunications were in their early stages and as a result, the tourism industry on Ko Mak took some time to become established.

With an area of 16 square kilometers, Ko Mak has 27 km of coastline, many long sandy beaches, and a few hills.