While we were in some protected waters during our Baltic cruise early in the summer, we were on open seas during some windy and not so placid conditions and I didn't notice any major movement. All of the Oceania ships have stablizers and the only time I noticed any movement was in the rear dining room one evening when we were leaving port However, I am sure you know that if you are concerned about motion sickness you should make sure and have a midship cabin on a lower deck.