All the ships are pretty stable and they do have stabilizers, (little underwater wings), that they deploy when at sea to further stabilize the ship. You ARE on a boat and they do rock. This can range from barely noticable to pretty gtood rocking depending on the weather. If you start to feel queezy simply go to the pursers desk and ask for some Mezcline which they will be happy to provide you. The lower and more central you are on the ship, the less rocking you will feel.