There are a number of ways you could be dreaming of the Titanic, and there are a few different meanings involved. If you dream about viewing the sinking ship as an observer or from afar, it means you'll soon be facing a situation that will require you to defend your morals and your reputation.
If you dream of being a passenger on the sinking ship, it represents a recent loss in confidence. It could be from a recent experience or a general lack of happiness and motivation.