Khao Sam Roi Yot National Park

The name means the mountain of three hundred peaks, and the park is a cluster of limestone karst hills rising abruptly from a coastal plain of Thailand's largest freshwater marsh, with beaches and mudflats between. It was the country's first coastal national park, declared in 1966. Its best-known feature is Tham Phraya Nakhon: a cave with a collapsed roof, reached by boat from Bang Pu and then a steep twenty-minute climb over rock, where a royal pavilion, the Khuha Kharuehat, was built in 1890 for a visit by Rama V and now sits in a shaft of sunlight that falls through the hole in the roof in the late morning. The marsh holds large numbers of waterbirds including migrants from November to March, and there are mangrove boardwalks, viewpoints and quiet beaches. The climb to the cave is genuinely steep and hot and defeats a good number of visitors.

What you actually see

• Tham Phraya Nakhon - the 1890 royal pavilion lit through the collapsed cave roof.
• The karst peaks - limestone hills rising straight from the coastal plain.
• The freshwater marsh - Thailand's largest, with migratory waterbirds.
• The beaches - quiet coast between the headlands.

When to go

November to February for weather and migrant birds. The cave light is best in the late morning on a clear day - aim to be inside between about ten and eleven.

Honest expectations

The cave climb is steep, rocky and hot, and takes twenty to thirty hard minutes after the boat. Macaques on the trail steal food. The light effect needs sun and the right hour. Foreign entry fees are higher than Thai.

Nearby

Pran Buri Forest Park is north; Kui Buri National Park is south.