My daughter suffers from extreme sea sickness. She tried all the traditional remedies previously suggested with no success.
I met a nurse who previously worked on a cruise ship and she told me the MD on the cruise ship recommended passengers take the over-the-counter antihistamine, Cetirizine 10mg. This is usually taken for allergies. The brand name in the U.S. is Zyrtec, in Canada it is Reactine.
My daughter would take it once a day at 4pm while on a cruise. The effects were amazing. She had no drowsiness and more importantly no further nausea or vomiting. She was able to enjoy her dinners at the main dining room and the ship's evening activities.
This may not work for you but it worked for her. I tried it on my Alaska cruise and it worked for me too.
She already has it purchased for her next cruise in February.