I too took refrigerated acidophilus before I started taking two digeste advantages a day, so I figured I might as well stop taking the refrigerated kind. Anyway, we called the dude at the organic food store we bought the acidophilus from, and he said that even the refridgerated kinds will last a good 5-7 days not refrigerated, as long as they are at room temperature. They do lose a little potency not being refrigerated but he said its not enough to make a difference. If you still are concerned, I would say pack a little cooler.
Have fun on your cruise!!!