Nam Tok Sarika is a beautiful 9 level waterfall. During the rainy season, the water flows bountifully from the mountains. In the dry season, the fall usually dries up to a trickle. It is a very popular water play area. During the rainy season, Thais flock from nearby Bangkok to revel in the cool, refreshing water.
At the entrance to the falls is a parking area with restaurants and shops to provide for the many Thai visitors. You can buy souvenirs, handicrafts and clothes. Although these are tourist shops, they are aiming at the Thai market so the prices are much more competitive than you will find at the western tourist resorts.
From the parking area, you walk 400 meters to the base of the falls. The water flows over rocks and through forest. There are some grassy areas that are ideal to set up base and have a picnic.
From here, you can walk up the 9 levels of the fall. The water tumbles over the rocks and there are many drop pools where you can take a refreshing dip in the cool mountain water. Small fish swim in the water and they will take food straight from your hands.
If you walk all the way to the top, you come to the main fall. The top of this fall is 200 meters above the 9th level. Here the water falls into the deepest drop pool and you can have a truly invigorating swim under the falling water.
Another point of interest here is Sarika Cave. The revered monk "Luang Pu Man" resided and meditated in this cave during his religious missions from 1917 to 1920. Today monks and nuns still reside within the cave. You can look around the cave and there is a small temple at the top of the hill.
The area is part of Khao Yai National Park and they usually collect an entrance fee, which is 100 baht for foreigners.
From Nakon Nayok town, take route 3049 north towards the foothills of Khao Yai and the waterfalls area. The waterfalls are signposted. About 12km out of town the road forks and you need to take the left road (3050). Drive along this winding country road for another 3km and you reach the parking area.