The ferry combines the idea of public transportation (moving with the crowd toward conformity) with being on a ship (exploring emotions and feelings.) If you are waiting for a ferry, you may be too concerned with the idea of acceptance and are not able to express your real feelings. Since you are waiting, you may be giving the power to be fulfilled and autonomous in life to others, or to the whims of fate. The message might be to stop expecting and take responsibility for how you feel.
The condition of the water in relation to this type of boat ride can portray what is going on below 'the surface,' or how you really feel. Turbid water can represent old hurts that you need to process and release. Choppy or frightening water can represent a sense that you are not feeling in control of your emotions. Not being able to control what the ship is doing is the same thing as not taking responsibility for where you are going in life. The message of the dream might be to explore your feelings and sense of autonomy. If you wake up each day expecting difficulty - you will find it.
If the theme is more of solace and peace - you may have recently overcome a period of crisis and are moving happily with the flow of events. Receiving acknowledgment in the social sphere also manifests as traveling on a ship with others over smooth water.