Koh Phra Thong is an island in Khura Buri district, Phang Nga Province, southern Thailand in the Andaman Sea. It has an area of 88 km² and is separated from the mainland by a 7 metres deep canal. It is located off the west coast of Thailand and the closest town is the port town of Khura Burui, situated on the mainland about 10 km east.
Koh Phra Thong is the middle link in a chain of three islands. It is largely flat with expanses of inland savannah. It has long uninhabited beaches, fringed by coconut palms. There have always been a number of special natural features of Koh Phra Thong Island. It fronts onto over 5 miles of pristine beach on the Andaman sea and, in addition, over 4 miles of beach on a beautiful bay containing small picturesque islands with nice rocks and coral for snorkelling. It is also only 60 km from the Surin Islands, Richelieu Rock and only slightly further to the Similan Islands; both are renowned diving locations.
On the east side is a small fisherman’s village, Thapayoi and on the southeast end is another small village, Thung Dap. These villages total less than 300 inhabitants consisting of Moken, a rare tribe of sea gypsies, and Thais. The largest village, Thapayoi, has a school and a staffed community health centre.
To the north is Koh Ra. It is long, mountainous and covered in ancient rainforest. This terrain is quite inhospitable to humans but does house a large number of animal species.
To the south is Koh Kho Khao which is similar to Koh Phra Tong.
The island is part of the Mu Koh Ra - Koh Phra Thong National Park, established in 2001.