Henbane contains Scopolamine which is, in my opinion, the best drug available for long term motion sickness prevention.
Makes sense the Norse had it on a ship.
You can get patches of it today, one on the neck lasts 3 days, transforms a person who gets seasick easily to one with the stomach of a seasoned sailor. Never used the stuff myself but have had to get it prescribed for buddies who couldn’t keep their dinner (or water) down after dark.