Dreaming that you are seasick, has the symbolic significance of limiting condition in your life. Seasickness in your dream represents emotions or feelings that are dragging you down. You need to get rid of some conditions in your life, because these circumstances creates bad emotions and feelings.
Dream dictionary: Seasick dream meanings
If you are feeling seasick in a dream, then such dream warns you about suppressed feelings which letting you down. There is a need to overcome those emotions as it will lead you to depressed mood.