Reduce your sensory input by closing your eyes or lying flat on deck and looking up at the sky, not around the boat. Opposing sensory signals cause seasickness, reducing the stimulus helps alleviate the conflict and therefore your body's physical symptoms.
Distract yourself. While sensory confusion may cause seasickness, stress hormones aggravate these physical symptoms. Talk with a friend or suck on a piece of hard candy. Any activity that you find soothing or relaxing can help reduce the production of stress hormones and feelings of physical illness.
Breathe fresh air. Force yourself out on deck for regular intervals of fresh air. Holing yourself up inside the cabin exposes you to diesel fumes and other pungent aromas which can exacerbate seasickness. If you're trapped in the cabin during a rainstorm, use aroma therapy such as lavender or mint to mask other problematic odors like gasoline or smoke.
