Our larger ships are more stable with heavier weight and therefore are less prone to rolling motion. Most ships are so large and well-stabilized that it doesn’t even feel like you’re moving, especially in calmer waters. The middle of the ship tends to have less motion, as it is the natural balance point.
If you are prone to seasickness, you could consider cruise routes with fewer sea days. Port intensive cruises will provide you the opportunity to spend more time on land. You could also consult your physician for a drug or alternative remedy if you’re prone to motion sickness.