Tat Leuk is a small waterfall, but it's a beautiful place to camp for the night. You can swim above the falls if the water isn't too shallow, and the visitor centre has some information about the area, including a detailed guide to the 1.5km-long Huay Bon Nature Trail.
The visitor centre attendant can arrange local treks for between 60,000K and 160,000K, and rents quality four-person tents for 40,000K, plus hammocks, mattresses, mosquito nets and sleeping bags for 10,000K each. There's a very basic restaurant (best supplemented with food you bring from outside), a small library of wildlife books and a pair of binoculars.
From the junction to Ban Hat Khai village, turn left and continue another 6km until you see a rough 4km road on the left, which leads to Tat Leuk.