Ko Pha-ngan (เกาะพะงัน; ) 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 Hat 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 (estimated 10 hr average walking time) * From mainland: about 55 km * From Ko Samui: about 15 km * From Ko Tao: about 35 km * Main town: Thong Sala * Highest Point: Khao Ra, 630 m