Koh Samui Surat Thani Province (or Koh Samui, Thailand ), or just Samui, as it often is, on the spot, is an island on the east coast of the Isthmus of Kra in Thailand, near the town of Surat Thani continent. E 'third largest island in Thailand, an area of 228.7 km2 and a population of over 50,000 (2008). And 'rich in natural resources, white sandy beaches, coral reefs and coconut palms.