Khao Sam Roi Yot National Park, the first coastal
national park of Thailand, was established in 1966 and covers 98 square kilometres (38 sq mi) of
Prachuap Khiri Khan Province. It includes a
limestone sub-range of the
Tenasserim Hills, freshwater marshes, mangrove forests and sandy beaches. The large Phraya Nakhon Cave, pictured here, has an opening in its roof through which sunlight streams. The historic Khuha Kharuehat Pavilion within the cave was built for a visit by King
Chulalongkorn in 1890 and is directly illuminated for a short period each day during certain months of the year. Later kings, including
Vajiravudh and
Bhumibol Adulyadej, have also visited the site.