So I presume there's a requirement that you have a visa for each country you visit on a cruise ship, although I've never done one.
However, if you're passing a country that you're not actually stopping at, and a passenger gets ill (eg the recent norovirus outbreaks that one of my friends was part of on a Europe cruise) and needs to be airlifted to a hospital, how do they choose where to send them, and what if it's a country you don't have a visa for?