I am so excited for you for your upcoming cruise to Alaska!
As for seasickness, the best remedy I've ever found is a green apple. This was told to me by a crew member when I was cruising while in my first trimester of pregnancy and didn't want to take any meds. They're also free, and usually readily available on the ship.
Another idea is ginger. You should be able to find these in a health food store...but even a glass of ginger ale might help.
Before taking any OTC meds, please consult your physician.
Hope you enjoy Alaska as much as we did!