Ko Samui island of Surat Thani Province (or Koh Samui, Thai: เกาะสมุย), or often, simply Samui as it is referred to by locals, is an island off the east coast of the Kra Isthmus in Thailand, close to the mainland Surat Thani town.

It is Thailand’s third largest island, with an area of 228.7 km2 and a population of over 50,000 (2008).

It is rich with natural resources, white sandy beaches, coral reefs and coconut trees.