Always pack a shawl or pashmina. Most restaurants and theaters on ships are air-conditioned and those venues can get chilly in the evenings. Shawls take up minimal space or weight in your suitcase and add a touch of elegance and color to evening outfits.
A common misnomer with cruising is there will be thousands of other guests onboard a floating Mall-of-America-sized vessel, surrounded by endless seas. Much to the contrary, a plethora of renowned cruise lines have ships that hold only 300 passengers.