Are Cruises Bad for the Environment?

In 2018, over 27 million people embarked on a cruise ship holiday – equating to nearly 250 colossal metal cities chugging through our oceans every year. With these numbers expected to increase every year, it is more important than ever to look at the environmental impact of cruise ships. 

Many people think of our oceans as an unknown and endless universe, separate from our own. This is certainly not the case. Around 70% of our planet’s surface consists of oceans which are essential to our survival as a species. As we look under the surface at the environmental impact of cruise liners, we find a shipload of shocking facts.

Are cruises bad for the environment? Yes, current cruise ships are bad for the environment. 

When one individual boards a cruise liner, their personal carbon footprint is three times higher as it would be on land. With an average of 3,000 passengers on each cruise ship, you can clearly see how much of an impact these holidays can have on the environment. 

Let’s take a closer look at some of the factors that make cruises so bad for the environment. 

Air Pollution

Cruise liners predominantly run on diesel engines and gas turbines and frequently burn fuel oil. This produces all the nasty air pollutants that we have come to hate: sulfur dioxide, carbon dioxide, nitrogen oxide, and particle emissions – all of which have a detrimental impact on the environment. 

Sulfur Dioxide 

In 2017 it was found that the world’s largest luxury cruise operators, Carnival Corporation, emitted ten times more sulfur dioxide around European coastlines than the entire 260 million cars in the continent combined.

Sulfur dioxide, when mixed with air and water, creates sulfuric acid – the lead cause of acid rain. This directly causes the acidification of both terrestrial and aquatic environments which can lead to habitat loss and species extinction. 

Carbon Dioxide

Look, I don’t need to bore you with the impacts of carbon dioxide – everyone knows now. It’s bad.

Looking at one cruise company’s latest environmental report, their ships emit 1.17 lbs. of CO2 per passenger mile. Embarking on their 1,826-mile-long Caribbean cruise would emit nearly a ton of carbon dioxide per passenger. That is the equivalent of flying 6 passengers to the Caribbean.

How do they get away with it? You would like to think that travel companies of this size would be forced to conform to some set of rules – well they do, but these giant corporations can hop through loopholes to continue to maximize their profits at the cost of the environment. The International Maritime Organization (IMO) has regulations in place that all cruise lines must follow. 

There are much cleaner fuel alternatives that the ships could be using, but these are much more expensive. So, what do the cruise lines do? Cheat. They use scrubbers to essentially wash the cheap fuel that they burn to meet IMO requirements and discharge the pollutants created directly into the ocean. While some countries are realizing this and are banning the use of scrubbers in their waters, the laws in international waters are never enforced.

Let us just compare the emissions from one large cruise ship to the equivalent number of cars:

Emissions Equivalent No. of Cars
Carbon Dioxide (CO2)83,678
Nitrogen Oxide (NOx)421,153
Particle Emissions1,000,000
Sulfur Dioxide376,000,000

Due to the obscene amount of pollution, the air quality onboard large cruise liners can be as bad as Delhi, Shanghai, and other polluted cities. 

Even when the ships are in harbor, they often leave their engines running to avoid paying hefty shore-side taxes on electricity. This has made major ports around the world a cesspool for pollutants. Barcelona now has the most polluted port in Europe due to being an extremely popular cruise ship destination. In 2017 over 32 tons of sulfur oxide was deposited into their waters.

“Cruise companies create a picture of being a bright, clean and environmentally friendly tourism sector. But the opposite is true. One cruise ship emits as many air pollutants as five million cars going the same distance because these ships use heavy fuel that on land would have to be disposed of as hazardous waste.” – Daniel Rieger, transport officer at German environment group Nabu.

Water Pollution

Sadly, it is not only the atmosphere that the cruise ships are polluting. They are also damaging the seas and oceans that their entire business relies on.

When you have over 3,000 people crammed inside a metal tanker you are bound to create a lot of waste. 

  1. Sewage – Untreated human waste – After an endless seafood buffet, there’s a lot of it.
  2. Graywater – All non-biological waste fluid from kitchens, sinks, showers, etc.
  3. Solid Waste – Trash such as plastic, glass, paper, cans, are all incinerated onboard cruise ships.

So where do all these byproducts end up? You guessed it. The ocean.

The only regulation on raw sewage dumping is that it must be done no less than three miles from shore. Because after three miles the fragile ecosystems can no longer be damaged… right? 

All waste is supposed to be treated, but again we are talking about huge corporations that are hellbent on making money. Whenever there is an easier, cheaper way – they will do it. 

It is no wonder that major cruise lines are often fined for illegally dumping waste products directly into the ocean. That is only when they are caught! Imagine how many ships get away with this waste dumping when they are out on the open ocean.

Carnival Cruises were fined over $20 million in 2019 for conspiracy and the obstruction of justice for discharging vast quantities of oil, plastics, and other waste products into the sea. 

Carnival admitted to committing serious environmental crimes such as dumping graywater in Alaska’s Glacier Bay National Park and discharging plastic and food waste in the Bahamas, which poses a serious threat to marine life.

Heavy Fuel Oil

Cruise ships are massive in size compared to other marine vessels, meaning they burn much more heavy fuel oil – one of the ‘dirtiest’ fossil fuels available. This oil contains hazardous levels of sulfur, heavy metals, and other major pollutants.

Large cruise liners use ~150 tons of heavy fuel oil every day. The polluted bilge water created then combines with oceanic water, causing serious contamination. Exposure to heavy fuel oil is toxic to wildlife and extremely damaging to the environment.

Another environmental impact arises from anti-fouling paint used on the ship’s hull. This paint has the potential to leach toxic metal compounds into the ocean, which can then end up in complex marine food chains. 

Noise Pollution

Cruise ships are loud. Disruptive noise pollution from large vessels can directly affect marine mammals such as whales and dolphins. 

Both low and high frequency sounds emitted by cruise ships can seriously affect baleen whales and other large marine mammals – their complex communication systems and prey location techniques can be hindered by these unnatural sounds.

Ballast Water Pollution

Like all other large ships, cruise liners use huge amounts of ballast water to keep the boat stable while moving. This water can be topped up in one location and transported, literally around the globe, to another. This can pose a huge threat to marine ecosystems as the water is filled with innumerable amounts of microbes and vegetation alongside a myriad of small invertebrate species (plankton, algae, fish, etc). 

This has the potential to introduce invasive species into new environments, where they can out-compete local wildlife and introduce novel diseases and parasites. This can change the entire ecology of an ecosystem. 

One example of ballast water pollution is the introduction of comb jellyfish into the Black Sea. The jellies were transported in ballast water from the American coastline in 1982. Their prey consists of zooplankton, fish eggs, and larvae – all of which are a crucial component of the local food web. Due to the lack of natural predators in their new environment by 1995 the comb jellyfish made up 90% of the entire Black Sea biomass. This directly caused the collapse of Black Sea fisheries and drastically reduced the number of fish, dolphins, and other species within the ecosystem. 

Physical Destruction of Marine Life

It isn’t just the obscene amounts of air and water pollution that makes cruise ships bad for the environment. They also cause the destruction of wildlife and habitats by coming into direct contact with animals and fragile ecosystems. 

Cruise ships can pose a serious threat to coral reefs. The entry into shallow waters and anchoring on undisturbed reefs can damage fragile coral that will take hundreds of years to rebuild. Back in 2017, a British cruise ship crashed into a coral reef off the coast of Indonesia, destroying over 17,000 square feet of reef and causing more than $19 million in irreversible damage.

Additionally, it is not uncommon for whales to collide with the hull or propellers of large ships which can seriously injure and slaughter these gentle giants. 


There is simply no room for debate – cruise ships are bad for the environment. They are in fact one of the worst vacations within the travel industry. These floating cities emit mind-boggling levels of air and water pollution, running solely on money-making business models. 

Friends of the Earth (FoE) is an international network of environmental organizations. They have been advocates for cruise line reform for years and provide every cruise company a yearly report card to compare their environmental footprint, graded A-F. The results may shock you.

The factors that they are scored on include: 

  • Sewage Treatment 
  • Air Pollution Reduction
  • Water Quality Compliance
  • Transparency 
  • Criminal Violations

Out of the eighteen major cruise lines, half were given a grade of F, the worst available score. Eight also possessed criminal violations! The remaining liners all received grade D, except Disney Cruise Line which was awarded an unprecedented grade B-.

If you compare this 2020 report card to the one created back in 2016 where only four lines received a grade of F the rest obtaining D’s and C’s. It is worrying that cruise ship’s environmental footprint are worsening instead of improving. 

“The industry represents itself as a benefactor for the ocean, but we think that’s not the case with all of these lines”Marcie Keever, Director of the oceans and vessels program at FoE

What Can Be Done?

Cruise companies are certainly aware of the public’s concern, yet the important changes are failing to be made. The implementation of just a few simple changes would exhibit a drastic improvement in cruise liner’s impact on the environment. 

The use of ‘closed loop scrubbers’ should be universal. These scrubbers wash the ship’s dirty fuel in the exact same way but store the harmful pollutants for treatment on land instead of simply discharging it into the sea.

Enforcing the use of cleaner fuels, such a liquified natural gas, would significantly reduce the emissions of cruise ships. Sulfur emissions would drop by 99% and nitrogen oxide by 85%. While newly constructed boats are looking towards LNG fuels, there is still a long way to go to reduce air pollution generated by cruise vessels. 

Stricter regulations along with harsher taxes and penalties should be applied throughout the cruise line industry to prevent sewage, graywater, and ballast water dumping as well as reducing emissions.

As innovative technology advances, more environmentally friendly options will become available. The construction of solar and wind powered cruise ships is on the horizon, with a prototype already under construction in Japan.

What Can YOU Do? 

We all have the power to make our own choices in life, so why not base these choices around the environment. If people refrain from going on cruises, these polluting companies they will be forced to change at a much faster rate in order to survive.

Whenever possible opt for a more environmentally friendly form of travel, it’s not as if this is difficult – literally any other method of transport is better than a cruise ship! But if you are intent on taking a cruise, do your research – try and find the cruise line that impacts the environment the least. We only have one planet after all.

Lloyd Heathfield

Lloyd Heathfield is a Biological Science graduate who has always had a passion for innovative technology, especially that of an environmental nature. Lloyd now works in the solar energy sector.

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