The Phetchaburi River (Thai: แม่น้ำเพชรบุรี, RTGS: Maenam Phetchaburi, pronounced [mɛ̂ːnáːm pʰét.t͡ɕʰā.bū.rīː]) is a river in western Thailand. It has its source in the Tenasserim Hills, in the Kaeng Krachan National Park, Kaeng Krachan district and flows through Tha Yang, Ban Lat, Mueang Phetchaburi and mouths into the Bay of Bangkok in Ban Laem district. It is 210 kilometres (130 mi) long, most of which is within the Phetchaburi Province. It is the backbone of this province.
In addition, the water in this river was used in the coronation ceremony of the Thai Kings in each reign.
13°15′57″N 99°56′32″E / 13.2657°N 99.9423°E