I get motion sickness, too.

I had read a fellow FTers trip report(bocastephen), which included a section of a sightseeing cruise out of Seward, Alaska. Bocastephen had done some research on motion sickness medicine and found Scopace(a pill form of the scopolamine patch) had worked fabulously for others. It also worked great for Bocastephen and travel companions on their cruise. Based on what the FTer posted, I got a prescription for it. Before we went to Alaska, I tried it out at home. One of the things that makes me most sick is trying to read in a moving car. So I figured I'd give it a go, and took a book along while the Mrs. ran some errands. My brain kept telling me that this isn't good, but my stomach said "eh, whatever, I'm good."

When we went to Alaska, we wanted to do a similar sightseeing cruise out of Seward, in addition to a float plane excursion in Juneau later. We used the Scopace on the sightseeing cruise. Mind you this was on a not very big boat and included a full buffet shortly after departure. When we got to the mouth of the bay/sound(entering gulf of Alaska), 50% or more of the passengers were running to the bathroom. Thanks to Scopace, we were not included in that group of people.

The swaying of our full size cruise ship later in the trip didn't bother me, though, so I guess I'm not extremely susceptible. But Scopace has allowed me to do things I never thought I could without getting sick. I highly recommend it.

Other than that, as others have posted, try to get on a newer ship which should have the most current technology for motion control.