Ko Samui, Thailand

Beginning in the 19th century, a significant number of Chinese immigrants moved to many areas in Thailand, including Ko Samui. Most of these individuals were traders moving from Hainan, who culturally assimilated into the majority Thai society on the island. While much of these individuals' Chinese culture and identity have not been preserved, a number of Hainanese temples and communities still exist on Ko Samui. It was these immigrants who first began cotton and coconut plantations on the island, transporting them to the mainland on boats known as panuk lang si. As a result, these Thai-Chinese individuals tended to live closer to the beaches of Ko Samui, in contrast to the ethnic Thai individuals who lived further inland.

During World War II, Ko Samui was used by Japan as a base of operations in conjunction with Thailand's Navy. It is believed that, as a result of conflicts between the Allies and Japan, the area around the island contains a number of shipwrecks from the era. Locals reported a large explosion around that time, which academic Paul Chambers attributed to a Japanese tanker being bombed alongside Ko Samui on 15 June 1945.

In the 1960s, two dengue hemorrhagic fever (DHF) epidemics occurred on Ko Samui.

Until the late 20th century, Ko 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 kilometres (9.3 mi) journey from one side of the island to the other could involve a whole-day trek through the mountainous central jungles.

At first, tourists were primarily backpackers to whom locals provided basic accommodations. However, as Bangkok, Pattaya, and Phuket started to become major tourist destinations in the 1980s, Ko Samui began to attract significant foreign investment and travelers. The first era of development projects began at Chaweng Beach, followed by a steady outgrowth of resorts across the rest of the island. This period of economic growth was primarily the result of Thailand's Fifth

National Economic and Social Development Plan, which lasted from 1982 until 1986. In 1985, the Tourism Authority of Thailand (TAT) launched the Master Plan for Tourism Development of Ko Samui/Surat Thani.

In 1989, Samui Airport was constructed, facilitating a spike in mass tourism growth on the island during the 1990s. As a result of the increased income from tourism, Thailand's central government began reorganizing local administrative procedures on the island. Leases and joint ventures also came to replace direct land sales during this period, especially as the devaluation of the Thai baht and political instability in Indonesia led many to view Ko Samui as an affordable and relatively safe alternative destination. DHF outbreaks continued to occur on the island following the 1960 epidemics, with an incidence of nearly 500 cases per 100,000 during one outbreak in 1995, potentially impacting tourism during the period.

Economic growth has brought not only prosperity but also major changes to the island's environment and culture, including "explosive tensions" between rich and poor residents and crime linked to that or otherwise.

On 11 April 2015, a car bomb packed inside a pickup truck stolen from the southern border province of Yala, exploded in the underground car park of the Central Festival Samui shopping mall. The blast injured seven people, six Thai nationals and a 12-year-old Italian girl, who sustained minor injuries and were quickly treated and discharged. Because the vehicle originated from Yala, one of Thailand's southernmost, Muslim-majority provinces affected by the Southern Thailand insurgency, authorities initially suspected a connection to southern militant networks. Government and military officials also investigated potential links to domestic political tensions and anti-coup elements.

On 4 March 2022, Australian cricketer Shane Warne died of a heart attack at the age of 52, while on holiday in Ko Samui.