Pang Sida is the eastern end of the great forest belt that stretches across north-eastern Thailand from Khao Yai to the Cambodian border, a block of jungle, waterfalls and rolling hills in Sa Kaeo province. Together with Khao Yai, Thap Lan, Ta Phraya and a wildlife sanctuary, it makes up the Dong Phayayen–Khao Yai Forest Complex, a World Heritage site that protects some of the best remaining monsoon forest in mainland South-east Asia.
It is less visited than Khao Yai, which is precisely its charm. The access roads from Sa Kaeo run through farmland, cassava and sugarcane fields before the forest closes in, and inside the park the road climbs gently past streams and viewpoints. The surface is generally good, but potholes, wandering dogs and sudden rain are part of the deal. The rainy season, from roughly May to October, brings the forest to life and fills the waterfalls, though it also makes the roads slick. In the cooler months from November to February the riding is most comfortable, and the mornings can even feel fresh. Remember that Thailand drives on the left.
The park is famous among nature lovers for its butterflies. In the rainy season, clouds of them gather at puddles along the roads and streams, yellow and white and sulphur-green, rising around you as you pass. Pang Sida Waterfall and several smaller falls tumble over sandstone ledges into pools. Elephants, gibbons, hornbills and deer live here, though the shy ones will hear you long before you see them. Listen for the whooping calls of gibbons in the early morning.
This border region carries layers of history. Not far east lies the frontier with Cambodia, crossed at Aranyaprathet, and the area saw refugee camps and fighting during the Khmer Rouge years and their aftermath. Today it is quiet farming country, and Sa Kaeo itself is a modest provincial town with markets, temples and some of the best som tam you can hope to find.
Fuel stations are plentiful along the main highways, and Sa Kaeo, about thirty kilometres away, has everything from fuel to repairs and simple hotels. Inside the park, facilities are basic: a visitor centre, camping and simple food. Carry water, a rain shell and insect repellent, and expect a small entrance fee.