The Karnaphuli River is central to Chittagong's identity, carrying port traffic, ferry movement, riverside industry, and the everyday geography of Bangladesh's main seaport. It is not a manicured attraction, but it is one of the clearest ways to understand why the city is where it is.
Views from bridges, ghats, and riverside areas are most interesting when treated as working-city observation rather than leisure cruising. Go with local guidance and be realistic about traffic, access, and industrial surroundings.