Koh Samui is an island off the east coast of the Kra Isthmus in Thailand. Geographically in the Chumphon Archipelago, it is administratively part of Surat Thani Province. Ko Samui is Thailand's second-largest island after Phuket, with an area of 228.7 km2, a population of over 63,000 and an annual tourist population of 1.5 million.
Abundant natural resources, white sandy beaches, coral reefs, and coconut trees are present on the island.
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".
Until the late-20th century, Koh Samui was an isolated self-sufficient community, having little connection with the mainland of Thailand. The island was without roads until the early 1970s, and the 15 km journey from one side of the island to the other could involve a whole-day trek through the mountainous central jungles.
Koh Samui's economy now is based primarily on a successful tourist industry, as well as exports of coconut and rubber.
Economic growth has brought not only prosperity, but also major changes to the island's environment and culture, a source of conflict between local residents and newcomers from other parts of Thailand and elsewhere. Reflecting Samui's growth as a tourist destination, the Cunard ship MS Queen Victoria (a 2,000-plus passenger ship) docked at Samui during its 2008 world cruise.