River-based public transport: Why won't Paris jump on board?

Given the magnitude of transport-problems in many large cities, the potential of rivers to serve as transport arteries is being recognized once again. However, some world cities, such as Paris, have failed to maximize their river potential. The Seine remains underutilized by mass commuter ferries serving the local population. Why, in the modern era, has Paris not taken advantage of its river for commuter transport? Will it do so in the future? This article answers these questions, which are important at the present time of grave sustainability concerns. The identified barriers include: (a) funding constraints; (b) competition by other modes; (c) lack of political and institutional will; (d) lack of opportunity; (e) local legislation; and (f) technical issues. The first three are common worldwide while the last three are specific to Paris.