Ko Pha-ngan is an island in the Gulf of Thailand in southeast Thailand in Surat Thani Province. Ko Pha-ngan is best known for its Full Moon Party at Haad Rin Beach. Ko Pha-ngan has two sister islands: the larger Ko Samui to the south and the smaller Ko Tao to the north.
Estimated perimeter: 40 km
From mainland: about 55 km
Wikipedia https://en.wikipedia.org/wiki/Ko_Pha-ngan
Coordinates 9°44'37.395" N 100°1'32.351" E