One of the biggest tipping questions, however, is what should you leave for your room steward. Technically, there's no need for additional gratuity, but most people do leave their cabin attendant something extra.

Carnival Cruise Line has made reducing food waste one of its key missions. It has tackled that in a number of ways, from some that are passenger-facing, like changing its main dining room menus, to having food biodigesters on all its ships.

A common trend for offering extra gratuities is a controversial practice among guests, but what does Carnival Cruise Line say?

Multiple ships from the cruise line are stuck at sea, and the company has angry passengers as well as many who have been understanding.