Most people don't get motion sickness while driving a car or piloting a boat/plane; the reason being because you're directly effecting the action of the vessel, you see what actions you have to take to steer a clear passage, you anticipate and react to the dynamic forces that result from such actions. Your mind/body kinesthetics are synchronized, your vestibular senses unconfounded, and you don't develop the nausea associated with motion sickness.
Here's how to achieve that state as a passenger on a diveboat:
Look not only at the Horizon, but also at the railing of the boat in the foreground --and see how it all moves relative to each other as the boat makes way through the swells. Memorize that movement and close your eyes, feel the boat's rhythm moving through the swells, and "see" that railing/horizon movement in your mind's eye. Anticipate where that railing/horizon orientation will be when you open your eyes . . .and finally open your eyes to see it and confirm it. Convince your mind and inner ear that you are in dynamic motion based on your sense of balance, tactile/kinesthetic feedback, and coordinating-synchronizing it all with the movement pattern of the railing/horizon which you just memorized. . .
In other words . . .don't anticipate being seasick --anticipate being in control, knowing & feeling what the boat's motion is going to be. With practice of this simple visualization, you can even "quell the queasiness" in the roughest sea conditions --all without any medication of any kind.
Again --All you gotta do is look at the horizon, see how it moves relative to the boat's motion and memorize that pattern, and then get a feeling for the rhythm of the swells and synchronize it with horizon's motion. Now when you go down belowdecks, just play it all back in your "mind's eye" as you begin to feel & anticipate the boat's apparent motion --or even imagine the boat belowdecks is transparent and you can actually see the horizon & swells in sync with the boat's apparent motion-- it's all just visualization without medication and it works!
That's the visualization technique you gotta practice, and unfortunately it's difficult to do if you're concentrating on something else like setting up your gear, reading a book, watching a video, worrying about running out of ginger pills/dramamine/bonine etc. But once you get good at it, you can hold the malaise to a reasonable level even in stormy seas --a "four" for instance on a scale from 1 to 10, with "ten" being projectile vomiting, extreme nausea, hugging the rail and begging for someone to shoot you . . . (In my thirty hour passage from mainland Costa Rica to Cocos Island, I was cognitively exhausted performing the technique over an extended period, and just simply fell asleep naturally). . .
