Boating and Sight Seeing:
The boat ride services are generally hop-on hop-off services with pit stops close to the sightseeing spots. The tour operator will have two or more boats which will be moving at intervals along the same route, so one need not worry about being left behind. If you feel you want to take more time at a particular sight, you can hop-off at that stop and come back after some time. The trick is to just ask at the stop about the timings of the next ferry.