Ko Samet is one of the eastern seaboard islands of Thailand. It is in the Gulf of Thailand off the coastline of the Thai province of Rayong, approximately 220 kilometres southeast of Bangkok. Ko Samet is the largest and westernmost of a cluster of islands not far from the coast. Ko Samet measures 6.8 km from north to south. At its closest point to the mainland, the island is 2.6 km
south of mainland Rayong Province; however the actual travelling
distancefrom the main commercial tourist pier in the town of
Phe to the island's closest tourist beach is about 10 km.
In 1981, the Royal Forest Department declared the archipelago of Samet, along with nine other small islands, the headland of Khao Laem Ya, and the 11 km Mae Ramphueng Beach to be a national park, and thus Ko Samet is under the protection of the National Parks Division of the Thai government.