Chumphon is on the Isthmus of Kra, the narrow landbridge connecting the Malay Peninsula with the mainland of Thailand. To the west are the hills of the Phuket mountain range and its northern continuation, the Tenasserim Hills, while the east is the more flat land on the coast of the Gulf of Thailand. The main river is the Lang Suan River, which originates in Phato District. With a 222 kilometre-long coastline and 44 islands, the Chumphon Archipelago, Chumphon has waterfalls, peaceful beaches, green forests, mangroves, and rivers.[