Ko Taen (or Koh Tan) is an island, approximately 15 kilometers off the mainland and 5 kilometers south of Koh Samui in the Gulf of Thailand. It is part of the Samui archipelago (Mu Koh Samu), which includes about 60 other islands. Just northwest of Koh Tan is the Mu Ko Ang Thong National Park.
Koh Tan is inhabited by about 50 people. Because of coming and going tourist activity on the island, the population fluctuates constantly. In the 1960s there were about 500 living people on the island. Because of higher wages on the neighbouring island of Koh Samui, most inhabitants emigrated there. This has led to the closure of the school and the health center on the island and most houses and huts now remain empty. The longstanding and current (2014) deputy mayor of Samui, Suraphong Viriyanon, is a descendant 0f a Chinese Koh Tan family. He was a driving but unsuccessful force in the 1990s, to turn Koh Tan into an island only for eco-tourists.
Koh Tan is minimally frequented by tourists. The island is accessible only by boat. The usual way to Koh Tan is from the fishing village Thong Krut on the south coast of Samui, which faces Koh Tan. It is possible to arrange individual day-trips to Koh Tan there. There are also companies offering trips to the island from other places which include a much longer trip on larger and more comfortable boats. The island has several beaches suitable for snorkeling. The island is surrounded by coral reefs, which survived and partly recovered from the widespread dynamite fishing in the region until the 1980s. Many small bungalows have been built on Koh Tan, especially since in the late 1990s, of which some can still be rented by small groups, but many of these businesses have given up. There are paths that are interesting for mountain bikers. Koh Tan features a large mangrove forest on the southwest coast with abundant wildlife. Monitor lizards can be seen during a walk through Koh Tan quite often. There is still a small temple in Koh Tan with a freshwater spring right on the beach.