Kaptai Lake the largest man-made freshwater body in Bangladesh. Though created primarily for hydroelectric power generation, it contributes to produce significant quantity of freshwater fishes, navigation, flood control and agriculture, etc. The reservoir was created by damming the river KARNAFULI near KAPTAI town in the CHITTAGONG HILL TRACTS (Latitude 22°09'N and Longitude 92°17'E). The lake is confined within the hill district RANGAMATI and embraces the upazilas of Rangamati Sadar, Kaptai, Nannerchar, Langadu, Baghaichhari, Barkal, Juraichhari and Belaichhari.
The 'H'-shaped it has two arms, joined by a narrow gorge near Shubalong, a part of the old Karnafuli river. Kasalong, the right arm of the lake, is fed by two streams, the Mayni and the KASALONG , in the north and laterally by the Karnafuli. The left arm, Rangamati-Kaptai is fed by two streams, the Chengi in the north and the RINKHYONG in the south. The purpose of creating this lake is primarily hydropower production. The hydropower project related to the construction of the lake is located in Kaptai Upazila of Chittagong Hill Tracts. According to the name of the dam site Kaptai, residents used to call it Kaptai Lake, which was also known as Karnafuli Lake in some documents.
After the completion of the construction of the Kaptai Dam, the spillway was closed in May of 1961. The Lake is the diverse variety of natural beauty, mountains, streams, sculpted high-low mountains, ominous water and green complexes all around. It is one of the largest artificial lakes in South Asia situated in the hill district of Rangamati. A lot of fish and biodiversity combinations in the lake water. On the mountains, fruits, forests, and medicinal plants and vegetables are available. In all, It has an extensive conservation of tourism, livestock, and biodiversity.