The edge of Khao Yai is a different country from the park itself. Where the forest road climbs from the plain, the hills above Wang Nam Khiao flatten into a high plateau of grass and farmland, with sunflower fields in the cool season, flower farms, and rows of fruit and vegetables, and the horizon is the dark wall of forest running up to the park boundary. The air here is cooler, and in the early mornings of December and January the valleys fill with mist that burns off by eight. It is easy to forget you are in the tropics.
The park sits on a high sandstone plateau, around eight hundred to a thousand metres, and its edge is steep, with the monsoon rain dropping on the windward slopes and feeding waterfalls on every side. Haew Suwat, a double cascade in the forest, appeared in a well-known film about backpackers, and is now a reliable stop for visitors. On the park's southern side, Haew Narok, a three-tier fall, is one of the largest in the country, and in the rainy season it thunders. Hornbills, gibbons and wild elephants live in the forest, and the elephants sometimes come out onto the roads.
Riding here is a matter of climbing and curving through the foothills. Roads from the Wang Nam Khiao side wind between farms and hills, with moderate gradients and good views, and the surface is generally decent, though tractors, trucks and cyclists use them. The route from Nakhon Nayok on the south side climbs through forest with long, tighter bends. Night riding is not wise, since animals cross the road after dark and drivers are sometimes erratic. Weekends are crowded with Bangkok visitors, so weekdays are calmer.
Small cafes and roadside stalls on the plateau sell coffee, grilled corn and fresh fruit. The best season is November to February, when the air is cool and the views clear. In the rainy season, expect fog, rain and leeches in the forest.