Many of today’s cruise ships are more or less small cities, feeding thousands of people a day.

They potentially have a huge environmental impact.

With some ships averaging nearly 8,000 people on board, the numbers are staggering: fuel burned, toilets flushed, and dishes washed.

Even french fries, something we take for granted, can have a huge environmental impact if not managed properly.

Today’s new generation of ships have entire decks devoted to nothing but waste management.

When some cruise lines, such as Princess, pull into ports in Alaska, they shut down their engines and generators.

They literally plug into local power grids, thus reducing their carbon emissions.

On Norwegian Cruise Line vessels, passengers can order french fries without guilt—at least about the cooking oil.

Their ships generate 20,000 liters of cooking oil per month.

But where does it go? NCL actually gives the spent cooking oil to farmers to be used for biofuel.

In real world terms, it is the equivalent of the oil used by 165 McDonald’s restaurants in just two months.

For more information about cruises, check out:

• Paying to Access WiFi on Cruise Ships
• How Do Travelers Actually Feel About Cruising?
• Cruise Lines Continue to Build More Ships

Keep reading for more travel tips.