Sitting at the heart of the 'Emerald Triangle' (a meeting of the Thai, Lao and Cambodian borders) this little-known national park is one of Thailand's wildest corners and healthiest forests. The 686-sq-km park's primary attraction is Namtok Huay Luang, a waterfall that plunges 45m in two parallel streams. A short trail from the visitor centre leads to a viewpoint and you can walk down 274 steps to the bottom where you can swim, though the water dries up around March.
About 150m downstream is Namtok Praon La-or, also a pretty picture. Rangers can take visitors on short bamboo-raft trips (300B for six people) above the falls, though for various reasons this activity is intermittent. The best time for this is between October and December. Between the waterfall and the lodging/visitor centre is Palan Pachad, a rocky field that features many wildflowers.
Resident fauna includes elephants, tigers, Malayan sun bears, barking deer, gibbons, black hornbills and endangered white-winged ducks, though you won't likely see them.
Stargazing is superb here, so consider spending the night. There are six well-worn bungalows plus a campsite 2km from Huay Luang. A restaurant opens at least 9am to 4pm daily at the waterfall, and snacks and drinks are sold at the lodging area.
There's no public transport to the park and not much traffic in the park, so you'll need your own transport; hitching requires patience.