Dreams about water are always about emotions. An ark is a very specific boat in the Bible in which Noah saved every type of species. This dream could be telling you that there is a need to seek a safe place if you are looking at the ark from the ground, or if you are on the ark, it could be telling you that you are in league with the right spiritual people.
If you are driving the ark, it could be a way of signifying that you are helping others in a spiritual journey. This could signify your ability to cope with and express your emotions. Are the waters calm or violent, clear or murky, etc.. or are you 'smooth sailing'? You may be ready to confront your subconscious and unknown aspects of yourself. The dream could be telling you not to rock the boat and to stay out of harm's way. Think about how you are feeling in the dream to know which of these meanings is most accurate.
To dream that you are trying to jump off the ark might suggest that you want to confront difficult emotions and approach your problems head on.