Why was I concerned? After all, my US passport was valid. While it wasn't a problem for our Caribbean sailings, in some instances it would have stopped me from traveling to certain foreign countries. For instance, Russia. The required amount of time you have to have remaining before your passport expires varies by country so it's a good idea to check when you are planning any trip. You can get that information from the US Department of State website.
According to the US Department of State:
"If possible, you should renew your passport approximately nine months before it expires. Some countries require that your passport be valid at least six months beyond the dates of your trip. Some airlines will not allow you to board if this requirement is not met."After our cruises, one of the first things I did when we got home was renew my passport.