In general, experienced cruisers feel the concern about sea sickness is overdone, perhaps more among first time cruisers. The larger ships have several stabilizers that even out the pitch and roll of the ship--but in heavy seas (i.e., waves 15 ft. or more), you can certainly feel some discomfort.
Many cruises these days tend to be in calm waters and the ships have gotten so large that their sheer size helps lessen the motion. Modern weather tracking devices help keep the ship sailing in calm waters by avoiding any storms. The improving technologies of large modern ships provide for better stabilizers that counter act the motion of the ocean.
If you think you are prone to sea sickness, there are some measures you can take to prevent it. Book your cruise in calm waters aboard a larger modern ship with stabilizers. Get a mid-ship, lower level inside cabin; those have the most stable ride. Get your cabin with beds that are parallel to the length of the ship; the rocking is usually easier for your body to handle than a rolling motion. Once on board, spend some time on deck and focus on a fixed point of the horizon. This helps your body to adjust to the motion.
Speak with your doctor before you leave for recommendations of preventative medications you could use. Some people find an acupressure bracelet around the wrists to be helpful. Avoid alcohol; it will only increase the symptoms of motion sickness.
There are so many sights to see, and you’ll want to bring back memories to share with your family and friends. What’s the best way to do this?