They will work for cruises but IMO are worthless for it. May as well take your birth certificate. You can't fly internationally with the card so if you got stranded by your ship and had to fly home you're just as boned as if you had no passport at all.

[–] xijinpingist@hexbear.net 3 points 2 weeks ago

An extra form of ID is always handy, I used mine to fly in the States because my drivers license had expired from disuse. I love not driving. Plus the passport card is also proof of citizenship and it fits in a wallet and doesn't get beat-up and stringy like your passport does. Plus if you lose it it's not a super tragedy, but if you lose your passport that is a big deal because it has all your visas in it and getting those back is a pain. Plus reporting a lost passport makes you suspicious because someone could be impersonating you. Brits on holiday used to run out of money and sell their passports. There was a way of steaming it open and putting someone else's photo in there so god knows who got into the UK with those.