Ko Samui is in the Gulf of Thailand, about 35 km northeast of Surat Thani town (9°N, 100°E). It is the most significant island in the Chumphon Archipelago. The island measures some 25 km at its widest point. To the north are the populated resort islands of Ko Phangan, Ko Tao, and Ko Nang Yuan. Close to Bangrak in NE Samui is the small uninhabited island of Koh Som, and to the northeast of Chaweng is the tiny Ko Matlang. In the southern direction are Ko Taen, Ko Matsum each of which have very small tourist facilities. To the far west are 44 other islands which together compose the Mu Ko Ang Thong National Park which is accessible by a day-trip boat tour from Ko Samui.