Kaptai Lake is the largest man-made freshwater lake in Bangladesh. Even though it was created mainly for hydroelectric power generation, it plays a vital role for producing freshwater fishes, power generation, flood control and agriculture, etc. This lake was invented by damming the Karnafuli river water near kaptai town in the Chittagong Hill Tracts. The Kaptai lake is limited within the hill district rangamati and embraces the upazilas of Rangamati Sadar, Barkal, Juraichhari, Kaptai, Nannerchar, Langadu, Belaichhari, and Baghaichhari. The Kaptai Lake's average depth is about 100 feet and maximum depth is about 500 feet.

During Pakistan period, Kaptai Lake building was begin with assistance of America in 1956 and it was completed in 1962. It cost around 50 crores taka at that time. Around 54 acres of agricultural land was sacrificed due to Kaptai Lake construction. Furthermore, 29 sq. km. area and 234 sq. km. of forest went under Kaptai Lake which resulted in 18 thousand house-less family at that time. At present, there are five units of electricity plant at Kaptai Lake which generates around 230 megawatt of electricity.

Tourism industry has been built in Rangamati surrounding Kaptai Lake. Visitors can enjoy many hanging bridges, hills along with lake, Chakma Rajbari, etc.