Thap Lan is the largest of the four parks in the Dong Phayayen–Khao Yai Forest Complex and the least visited. At 3,713 square kilometres, it stretches across the border of Prachinburi and Nakhon Ratchasima provinces. The terrain is dominated by dry dipterocarp and mixed deciduous forest on undulating plateau, quite different in character from the denser tropical forest of Khao Yai.
Because it attracts almost no foreign tourists, Thap Lan offers genuine solitude. The park has no paved loop road and facilities are basic. What it does have is large mammals — elephants, banteng, gaur — and some rewarding birdwatching along the Wang Nam Khiao corridor. A few trail options are accessible from the park headquarters near the town of Wang Nam Khiao.
Getting there requires your own transport. From Prachinburi town, head east on Route 33 toward Kabin Buri, then take Route 304 north; the park entrance is signposted off the Kabinburi-Nakhon Ratchasima road. A half-day visit is feasible from Prachinburi, but an overnight stay in Wang Nam Khiao — a cool-climate retreat popular with Bangkok residents — is more rewarding.