My husband!!! He loves to cruise as much as I do! Also, I can't narrow my choices of what I can't cruise without as I pack as if I'm never coming back.
But, the one thing I absolutely can't leave home without is my husband. !
Oddly enough it's a book of crossword puzzles. I do the ones in the newspaper everyday at home, so without a newspaper on board I'm lost. My husband always knows where to find me early in the mornings when we're cruising. Back of the Lido deck, cup of coffee and crossword in hand.