Emily, they are usually referred to as seasickness bands, but if you tell the druggist exactly what you just said, they'll know where to steer you. They will probably be on a shelf - look near the Dramamine.
Although I have friends who have used them with success, I have not had such good luck with them. That's why I recommended Bonine (or the non-drowsy version of Dramamine) in my previous post. That works for me. It's not way expensive - you could get both the bands and the Bonine; that way you'd be covered. Who knows - you may find that the gentle rocking doesn't bother you at all! I didn't take any medication at all my last cruise (just last week - wish I was still there!)
Have a great time! Karen