Ko Samui, often simply Samui as it is referred to by locals, is an island off the east coast of the Kra Isthmus in Thailand. It is located close to the mainland town of Surat Thani in Surat Thani Province. It is Thailand's second largest island after Phuket, with an area of 228.7 km2 and a population of over 63,000 attracting 1.5 million tourists per year. Ko Samui has abundant natural resources, white sandy beaches, coral reefs and coconut trees. It is part of Mu Ko Samui.
The island was probably first inhabited about 15 centuries ago, settled by fishermen from the Malay Peninsula and Southern China. It appears on Chinese maps dating back to 1687, under the name Pulo Cornam. The name Samui is mysterious in itself. Perhaps it is an extension of the name of one of the native trees, mui, or from the Malay word Saboey, meaning "safe haven". Ko is the Thai word for "island".