Ko Samui is in the
Gulf of Thailand, about northeast of Surat Thani town (9°N, 100°E). It is the largest island in the
Chumphon Archipelago, measuring about at its widest point. To the north are the populated resort islands of Ko Pha-ngan, Ko Tao, and Ko Nang Yuan. Close to Bangrak in northeast Samui is the small uninhabited island of Ko Som, and to the northeast of Chaweng is the tiny Ko Matlang. To the south are Ko Taen and Ko Matsum, each of which have small tourist facilities. To the far west are 44 other islands which together compose
Mu Ko Ang Thong National Park which is accessible by a day-trip boat tour from Ko Samui. The central part of Ko Samui is mostly tropical jungle with tree coverage and wildlife and its largest mountain, Khao Pom, peaking at . The lowland and coastal areas are connected by a -long road, encircling the island. Other concrete roads branch off to service other areas. The town of Nathon on the west coast is the closest town to the mainland and is the original capital which still houses many government offices. Two of the island's five main piers make Nathon the main port for all transportation from the mainland and the commercial centre for Samui residents. The transition from dependence on the local coconut industry and the continued growth and development of the tourist industry, as well as the northeastern location of the airport, has led to the increase of commercial activity in Chaweng and Bophut.
Climate Ko Samui has a
tropical monsoon climate according to the
Köppen climate classification, based on an analysis of 1971–2010 Thai Meteorological Department data. The climate is warm and humid for most of the year. In comparison to
Phuket and most of the rest of southern Thailand, Samui's weather is relatively drier (Samui receives about rain per year, and Phuket gets ). Phuket's
wet season is spread over six to eight months. Ko Samui has only two months with more than of rain. The heaviest precipitation typically falls in the time frame from mid October to early December. For the rest of the year, given the tropical climate, rain showers are brief; 20–60 minutes duration is typical. }}
Nature The jungles of Ko Samui are home to a number of notable waterfalls, including the Na Muang Waterfalls, the Hin Lad Waterfall, the Khun Si Waterfall, the Wang Sao Thong Waterfall, the Tang Rua Waterfall, the Tar Nim Waterfall, and the Lat Wanorn Waterfall. Many of these waterfalls are especially popular tourist destinations, despite a number of visitors experiencing severe injuries or death due to slips or falls around these areas. A number of fruit trees grow on the island, including
langsat,
durian, mamud, and mamuang thaai tor (the latter two of which are local
mango varieties). Macaques are forced by some farmers on the island to harvest coconuts, often under
threat of violence. Many
elephant sanctuaries exist on Ko Samui, but there are no standards for what constitutes a sanctuary in Thailand and unethical and unsafe practices such as elephant riding still occur. In one case in 2016, a British tourist was killed after being thrown from an elephant after its handler hit the animal several times. Amphibian species include the frogs
Limnonectes blythii,
Limnonectes doriae,
Polypedates leucomystax, and the caecilian
Ichthyophis supachaii. and
Cnemaspis siamensis, and
box jellyfish. It has been noted that the highest incidence of jellyfish-related deaths in Thailand have occurred on Ko Samui and
Ko Pha-ngan, with six of the seven cases of box jellyfish-related deaths from 1999 to 2015 occurring on those two islands. ==Demography==