Koh Pha Ngan is situated on the north of Koh Samui in the Gulf of Thailand. It is approximately 12 kilometers from the nearest border of Koh Samui and 100 kilometers from the northeast of Surat Thani province. There are six islands in Koh Pha Ngan group; Pha Ngan, Tao, Tae Nok, Tae Nai, Ma, and Nai Yuan.

Geography
2/3 of the Koh Pha Ngan is mountainous and covered with dense forest. The part of the east is covered with the series mountains with open seas until to the mountain of Luang in Surat Thani and Nakorn Sri Thammarat. The beautiful gulfs and beaches located on the west side. 70% of Koh Pha Ngan is mountainous and significant source of rivers. The important mountain peaks are Kao Rha, 627 meters, which is the highest peak in the north, Kao Mai Ngam, 535 meters, in the south, Kao Tah Luang, 478 meters in the northwest, and Kao Lad Mai Keaw, 378 meters in the east of Koh Pha Ngan.