Haew Narok Waterfall is the largest waterfall in the Khao Yai National Park dropping over 150 meter (492 ft.) from the top to the basal lake and it is one of the highest waterfalls I have seen in Thailand. Take the October-November months to visit, when the waterfall is at its most powerful.
Haew Narok Waterfall is in Khao Yai National Park, Thailand. It is located in the south side of the park in the area of Prachin Buri Province.
To begin, the trail starts off at the parking lot at 4325 ft. It is flat, paved, and wide. For about 0.3 mile, you will reach the wooden bridge where you have to cross over it the chocolate-like gorge which ultimately ends up feeding the waterfall.
Next section of the trail is relatively ascending and wide for about 0.4 mile then you reach the last section. The last section of the trail has a lot of steep stairs descending down to the base of waterfall for 0.3 miles. Some of the steps is so steep and may require to scramble. The trail stops at the overlook which is the upper most of the waterfall. The elevation gain is about 700 feet and the trail ends up at about 3625 ft.
FYI: If you would like to see the more comprehensive view of waterfall, you have to ask the ranger at the ranger station at the trailhead (parking lot) to serve you as a navigator. A ranger will navigate you to the non-maintained trail (it is off from the regular trail at an intersection before you start the last section, the stair section).