Passing through a canal in a dream can represent passing from one stage of life to another.
Movement through a canal can also represent birth. This could be a metaphorical birth rather than a literal one. For example, taking a boat or a ship through a canal in a dream can mean that you are going through a significant change or that you are starting something new in your life.
Because a canal is a relatively narrow, artificial structure, if you dream that you are in a canal it can be a sign that you have placed too many unnecessary restrictions on yourself, or that you are being too closed-minded. Your dream could be telling you that you need to be more creative or more flexible, or that you need to be more open to new ideas.