Those selling cruise holidays promise pristine waters, cloudless skies and sunny ports of call. Environmentally speaking, however, ocean travel can be a dicey proposition: every year, the industry consumes millions of tons of fuel and produces almost a billion tons of sewage. Left untreated, exhaust and raw sewage from ships can fog the air and pollute the water, potentially causing a host of ugly environmental and health effects that undermine the very natural beauty that cruise ships advertise to potential travelers.
