Even a family who cruises only once a year should invest in a passport. It is costly at first, but they are good for 10 years. That is only $8.00 a year per person if you break it down. You will then have the security of knowing that if you ever have to leave the country, you can do it at a moments notice. I went through years of hassle with a birth certificate with no raised seal, then when I finally got one, they told me it was no good because it was in my maiden name. I finally got a passport and it has been a blessing. When you return to this country from different places, you can clear customs much faster with a passport.