How environmentally friendly is your cruise holiday?

Cruises are a popular attraction for Americans on vacation, but a report card rating cruise lines’ efforts to reduce pollution may come as a rude shock
An estimated 24 million passengers are expected to cruise the world’s oceans in more than 220 cruise ships this year, up from 19.1 million in 2010. But these giant floating playgrounds leave an enormous environmental impact. Many large ocean liners run on giant diesel engines, which can stand at more than three stories tall and span t