The imposing karst Phadeng range, on the other side of the River Nam Song, is dotted with several caves (tham). Tham Phadeng Ang Ngeung, located in the side of the cliff, 50m above the ground, is home to a small lake between June and September. A little further north, the top of Pha Poak hill offers a fine view over Vang Vieng. A footpath between bamboo, ferns and teak trees leads to Tham Lusi, a small cave boasting attractive limestone concretions.