is one of the Eastern Seaboard Islands of Thailand. It is located in the Gulf of Thailand off the coastline of the Thai province of Rayong, Ko Samet is part of the Phe (Thai: เพ) Subdistrict of the Amphoe Mueang Rayong (Thai: เมืองระยอง, the capital district, or Amphoe Mueang), of Rayong province.
Popular with foreign tourists and as a weekend getaway for residents of nearby Bangkok, most of the island (excluding the Na Dan area) belongs to the Khao Laem Ya - Mu Ko Samet National Park.