Koh Samui is Thailand's third-largest island, an irregular square in shape and measuring about 55 kilometres in circumference. Unlike Thailand islands such as Phuket, Samui is dramatically hilly and with only a narrow strip of flatland around the edges - this is the reason Koh Samui is not hi-rise and built-up. Although the history of Samui is 90% about coconut farming and with little else of note, there's a strong Chinese influence due to traders and sailors.