Paddling a canoe in a dream represents an attempt to control your emotions, often when you are going through a difficult time in real life.
If you are paddling with difficulty, in rough water, you are trying to reign in your feelings but are having a hard time doing this. If you are alone in the canoe, you are afraid that others will react negatively to you if you let them know how you truly feel.
If your canoe overturns, so that you fall into the water, your dreaming mind is warning you that you cannot avoid dealing with your emotions; you will have to face them eventually.
A dream that you are canoeing successfully through the water without much trouble can mean that you are confident that you will be able to get through a crisis on your own.