TL;DR: Cruise ships emit roughly twice the CO2 of flying and staying in a hotel to the same destination, and most major cruise lines score poorly on transparency about sewage and water treatment according to Friends of the Earth's annual report card.
Is cruising ever sustainable? The evidence points to no, at least not compared with other ways to reach the same destination. The International Council on Clean Transportation, a nonprofit research group that has no stake in selling cruises or flights, found that passengers on even the most efficient cruise ships emit roughly twice as much CO2 as someone who flies to the same destination and stays in a hotel instead. That comparison matters because cruise marketing often frames a cruise as an efficient way to see multiple destinations in one trip, when the ship itself is the highest-emitting part of the vacation.
A separate analysis from Friends of the Earth, an environmental nonprofit that has published an annual cruise industry scorecard for over a decade, found that cruise-goers generate about eight times the daily carbon footprint of someone on a land-based vacation. Their comparison estimated about 421 kilograms of CO2 per day for a double-occupancy cruise departing Seattle, versus roughly 81 kilograms per day for a land vacation using a high-end hotel and carbon-heavy transportation. These are two different comparisons, cruise-vs-flying and cruise-vs-land-vacation, and both point the same direction.
Comparing Vacation Types
| Vacation Type | Relative CO2 Per Person | Source |
|---|---|---|
| Cruise (most efficient ships) | Roughly 2x a flight-plus-hotel trip to the same destination | International Council on Clean Transportation |
| Flight + hotel stay | Baseline comparison point | International Council on Clean Transportation |
| Land vacation (hotel + ground transport) | Roughly 1/8 of a cruise's daily footprint | Friends of the Earth |
Friends of the Earth's Cruise Ship Report Card
Friends of the Earth grades 21 major cruise lines and 243 individual ships across four categories: air pollution reduction, water quality and scrubber use, sewage treatment, and transparency. The results are lopsided. Carnival Cruise Line received a failing grade in the most recent scorecard, while Royal Caribbean International and Princess Cruises each scored a D-minus. Only a handful of lines, including Hurtigruten/HX Hurtigruten Expeditions, Disney, and Regent, scored above a D+.
The transparency category is where the industry looks worst as a whole. All 21 cruise lines scored poorly on sewage treatment because, per the report, none of them publicly report on how well their advanced treatment systems actually perform. That makes it difficult for a traveler to verify any individual line's environmental claims beyond taking the marketing at face value.
What's Actually Happening With Scrubbers and Sewage
Many cruise ships use exhaust gas scrubbers to reduce air pollution from burning heavy fuel oil. Open-loop scrubbers work by washing the exhaust with seawater, which pulls pollutants out of the air, but the wastewater, now carrying those pollutants, is typically discharged directly into the ocean rather than treated onshore. It's a real tradeoff: cleaner air immediately around the ship, dirtier water in its wake. Because none of the major lines publish performance data on their sewage systems either, per Friends of the Earth's findings, it's difficult for anyone outside the company to independently confirm how much of that waste stream is actually being treated versus discharged.
Are Any Cruise Options Actually Lower-Impact?
Relatively, yes. The lines that scored better on the Friends of the Earth report card, including Hurtigruten/HX, Disney, and Regent, tend to operate newer or smaller ships with more modern pollution controls, and some newer vessels are built to plug into shore power at port instead of idling their engines while docked. None of that makes a cruise lower-impact than flying and staying in a hotel; it just makes some cruise lines less damaging than others within the same category.
Lower-Impact Ways to Get an Ocean Trip
- Coastal ferries for shorter point-to-point ocean travel instead of a multi-day cruise itinerary.
- Train plus a coastal stay, covering similar scenery without the ship's fuel burn; see how the numbers actually compare in our train vs flying emissions breakdown.
- A land-based itinerary hitting the same ports a cruise would visit, using regional flights or driving between stops.
If you're the type of traveler who considers buying a carbon offset to cover a cruise or flight, it's worth reading what the research actually says first. Our look at whether flight carbon offsets actually work applies just as directly to offsetting a cruise. And if a hotel stay is part of your alternative itinerary, this guide to what Green Key and LEED hotel certifications actually require can help you pick one that backs up its claims.
The Bottom Line
Cruising is measurably more carbon-intensive than flying to the same destination and staying in a hotel, and the industry's own environmental scorecard shows most major lines failing on transparency about their sewage and water treatment. If the ocean is the draw, a ferry or a coastal train trip gets you there with a smaller footprint.
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