C.S.
My daughter just went on a cruise to the Caribbean. She was in shorts, summer dresses, and a swim suit most often. She did have to take a formal dinner dress. Check the cruise website and google the average weather for your stops.
Have FUN!
*Forgot to mention the ginger candy that you can pick up at Whole Foods. That will help with any motion sickness during and after the cruise. My daughter was fine during the cruise and when she got home she had dizzy spells for 2 days before I thought of picking up the ginger. $3.50/bag.