Believed to have been formed some 700,000 years ago, this volcanic, bottle-green crater lake is the main attraction around Ban Lung. The lake is ringed by thick green jungle and when viewed aerially, it forms a near perfect circle. The area is peaceful and a  visit here makes for a memorable day with morning swims  and wooden jetties to sun- bathe on. The visitors’ center can provide information on Ratanakiri’s ethnic minorities, a number of whom live near Ban Lung. Many of these tribes believe the lake to be an especially sacred place and according to their legends, monsters inhabit its clear waters. An easily navigable path runs around the lake and can be walked in an hour. Admission to the lake is administered by the local Tompuon tribe, with the money being used toward improving the condition of their villages. Visitors can reach the lake either on foot or by tuk-tuk from Ban Lung.