5. Lots of other things aren't included.

We've said it before, but we'll say it again: When you're figuring out the total cost of your cruise, do the math on how much onboard extras will add up to. If you have a latte every morning, soda or beer at lunch, wine with dinner, and you book shore excursions and onboard activities such as massages or wine tastings, you could end up with a hefty bill by the end of your trip. In addition, you'll want to factor in the required port fees, as well as the automated gratuities, which are common on all but the luxury lines, and even extras such as gym classes.