Nestled amid the limestone karsts of the Phu Hin Bun NPA is the stunningly beautiful Evening Gong Lake. The luminescent green waters spring from a subterranean river that filters through the limestone, making the water crystal clear. It's only about 30km northeast of Tha Khaek.
You must ask at the village before swimming in the lake. Once you get approval, only swim in the stream that flows from the lake, near the wooden footbridge, and not in the lake itself. Fishing is banned.
To get here, head north along Rte 13 and turn right (east) at Km 29 onto a dirt road. After 2km, turn right (south) again, and bump up over hills and through villages for 16km until you reach Ban Na Kheu. It's another 1km to the lake.