Depends if your cruise is staying in the inside passage or has days on the open sea. The cruise on the inside passage was very calm, described as like glass. We were on the upper deck for our first Alaska sail from Vancouver. But our daughter-in-law went from Fairbanks and the ship was pretty rocky, poor dear! We loved the Koningsdam (x2) deck 7 mid ship was our choice each time. You’ll have a treat, the food was excellent too, at least that was 4 years ago. Enjoy!