Your other response made a valid point. I'd also like to add that in the brain's non-verbal representation of concepts, the ocean can often stand for your mother or untapped creative potential.
If it were a nightmare by the ocean, I'd say repressed or undealt with emotion was bubbling to the surface. But since it's peaceful, I wonder if you have any feelings of desiring to break into a creative career/passion?
I also wonder if you have any desire to rekindle closeness with your mother?
Any of this relevant to you?