Karnaphuli is the largest river in Chittagong. A large hydroelectric power plant was built in the Kaptai region using this river and a water reservoir named Kaptai lake was formed for this hydropower station. It’s a beautiful blue lake which is located at Rangamati Sadar Upazila. The lake gives an amazing view of Chittagong hill tracts, forested trees and ceaseless flow of water together.