Posted 16/09/26
Cruise holidays are incredibly easy to sell.
Wake up somewhere new. Have breakfast overlooking the ocean. Spend the afternoon exploring a different destination. Then return to a floating resort with restaurants, swimming pools, entertainment and almost everything else you could possibly need. I understand the appeal.
But the more I have learned about our oceans, marine life and the environmental impact of tourism, the more I have questioned how sustainable cruise tourism can really be.
And this isn't simply about environmental campaigners criticising the cruise industry.
There is a growing body of scientific research looking at what cruise tourism actually does to the environments it passes through and the destinations it visits. Researchers have examined everything from greenhouse gas emissions and air pollution to wastewater, underwater noise, coral reef damage and the environmental consequences of building infrastructure for increasingly large ships. A major 2021 review of the subject concluded that cruise tourism can create significant environmental and human-health impacts across air, water and land, despite improvements in technology and management.[1]
So, are cruises becoming more sustainable?
Yes.
Does that mean cruising is sustainable?
I'm not convinced.
The Problem with Looking at One Ship at a Time
Cruise companies are investing heavily in sustainability.
There are ships capable of using shore power. Advanced wastewater treatment systems are becoming more common. Companies are improving energy efficiency, exploring alternative fuels and introducing new technologies designed to reduce emissions.
Those changes matter.
But I don't think sustainability can be measured simply by asking whether a new cruise ship is cleaner than an old one.
We also have to look at the bigger picture.
Cruise tourism is not just a ship.
It is the ship, the passengers, the fuel, the food, the water, the waste, the ports, the dredging, the infrastructure and the destinations themselves.
A 2023 review of research into cruise destinations reached a similar conclusion, arguing that the sustainability of cruise tourism needs to be considered at the destination and system level rather than through technological improvements on board individual vessels alone.[2]
And that is where things become much more complicated.
Cruise Ships are Floating Cities
A cruise ship isn't simply a means of getting from one destination to another.
It is effectively a floating hotel, restaurant, entertainment complex and transport system operating simultaneously. The largest cruise ships can accommodate around 7,600 passengers, alongside thousands of crew.[3] That means thousands of people need food, water, electricity, air conditioning, hot water, entertainment and waste management every day. The environmental impact therefore doesn't stop with the fuel used to move the ship. There is also the energy required to run everything on board, the water consumed and the waste generated. The US Environmental Protection Agency identifies several different waste streams produced by cruise ships, including sewage, greywater, oily bilge water, ballast water and solid waste.[4]
So when we talk about the environmental impact of cruising, we're not really talking about one problem.
We're talking about a whole collection of them.
The Carbon Problem
Cruise ships are particularly energy intensive because they are transporting people while simultaneously providing the facilities of a resort. They have to move a huge vessel through the ocean while also powering restaurants, cabins, pools, entertainment, lighting, air conditioning and everything else passengers expect. Transport & Environment estimates that an average cruise ship produces annual greenhouse gas emissions equivalent to around 19,000 cars.[5]
That doesn't mean cruise ships are responsible for anything close to the majority of global shipping emissions. They aren't.
But it does illustrate the enormous footprint of an individual cruise ship. And research shows that how a cruise ship is operated matters too. A 2024 study examining cruise activity and emissions in Chinese waters found that factors including fuel efficiency, vessel speed, routing and scheduling can influence emissions.[6]
That is actually quite encouraging.
It means some of the environmental impact isn't inevitable. Ships can slow down. Routes can be changed. Operations can become more efficient. Fuel consumption can be reduced. But reducing the impact of something isn't the same as removing it, and that's an important distinction throughout this debate.
The Ocean Isn't Silent
This is one of the issues I find particularly interesting.
Noise pollution is something most passengers will never think about. From the deck of a cruise ship, everything can seem peaceful. However underneath the surface, it is anything but.
Many marine mammals, such as dolphins and whales, rely heavily on sound to communicate, navigate, find prey and detect threats. Shipping is one of the major contributors to human-generated underwater noise, and cruise ships are part of that wider problem.
Research in Glacier Bay provides a particularly striking example. The National Park Service found that cruise ships could be detected above natural background noise for approximately 40 to 74 minutes during a single entry or exit from Glacier Bay.[7] And researchers found that slower speeds substantially reduced the amount of noise produced.
Imagine living in that environment. For an animal that relies on sound to understand its surroundings, a ship passing through isn't simply background scenery. It changes the acoustic environment.
Sometimes Ships Kill Wildlife
There is a more obvious danger too. Vessel strikes can kill or seriously injure marine mammals.
In June 2026, a 61-foot female fin whale was found dead on the bow of Royal Caribbean's Ovation of the Seas in Alaska. Initial findings indicated injuries consistent with a vessel strike, although the investigation into the incident was ongoing.[8]
One incident doesn't prove that cruise ships are responsible for the wider problem of whale mortality. And cruise ships are only one part of a much larger vessel-strike problem. But it illustrates something important. When enormous vessels and marine wildlife share the same space, collisions are possible. The solution isn't necessarily to stop ships from travelling through these environments. It is to manage vessel traffic in ways that reduce the risk. But again, that requires acknowledging that our presence in the ocean has consequences.
Coral Reefs Don't Get a Reset Button
This is where the physical footprint of cruise tourism becomes particularly uncomfortable. In 1988, Stephen H. Smith published research examining the impact of cruise-ship anchoring on coral reefs around Grand Cayman. The study recorded 3,150 square metres of previously intact coral reef destroyed by a single cruise ship anchoring for one day.[9] The authors subsequently estimated that recovery could take more than 50 years.
One ship. One day. Thousands of square metres of reef. Potentially decades to recover. That isn't theoretical damage. It was observed. And this isn't simply a historical problem.
A 2022 study examined cruise-ship anchoring in Barbados during the COVID-19 period and documented damage affecting thousands of square metres of coral reef. The researchers also highlighted the enormous size of modern cruise-ship anchors and the distance that anchor chains can travel across the seabed as a vessel swings.[10]
The important point isn't that every cruise ship destroys a coral reef. It doesn't. Anchoring can be managed through designated anchorages, mooring systems and restrictions in sensitive areas. The point is that when cruise-ship anchoring is poorly managed, the physical damage can be enormous. And coral reefs don't get a reset button.
The Environmental Cost of Making Room for Bigger Ships
Cruise tourism doesn't only affect reefs when a ship drops an anchor. Ships need ports. And ports need infrastructure. As cruise ships have become larger, some destinations have had to consider deeper channels, larger berths and other infrastructure changes to accommodate them.
Research from Bermuda looked specifically at the environmental and economic trade-offs involved in modifying cruise-ship approach channels.[11] The researchers found that accommodating larger ships could generate additional tourism revenue, but that dredging could also create environmental costs through direct coral damage and sedimentation.
This is one of the things I find most interesting about the cruise debate.
It isn't simply:
Cruises = bad.
There are genuine economic benefits. But there are also genuine environmental costs. And both need to be part of the calculation.
Falmouth in Jamaica provides another example of this conflict. The development of its cruise terminal required major marine infrastructure works, with coral and other marine habitats identified as part of the environmental considerations surrounding the project.[12]
So the question becomes:
How Much Environmental Change is Acceptable in Order to Accommodate Tourism?
And who gets to decide?
Wastewater is More Complicated than Sewage
Cruise ships produce a huge range of waste streams. Sewage is only one.
There is also greywater from showers, sinks, laundries and kitchens, along with bilge water, ballast water, food waste and other solid waste.[4] And scientists are now looking more closely at what is actually contained within cruise wastewater. A 2025 study analysed treated wastewater from three Arctic expedition cruise ships and identified more than 160 compounds, including pharmaceuticals, personal-care products and industrial chemicals.[13]
That doesn't mean cruise ships are simply dumping untreated sewage into the ocean. They aren't.
In fact, wastewater treatment has improved significantly. As of October 2025, CLIA reported that 234 ships, representing 82.4% of its member fleet, had advanced wastewater treatment systems.[14]
That's progress. But there is an important distinction here.
"82.4%" means 82.4% of CLIA's member fleet. It does not mean 82.4% of every cruise ship operating around the world.
And "treated" doesn't mean "nothing remains". It means the wastewater has gone through a treatment process. What that process removes, what remains afterwards and where the treated water is discharged are all important questions.
The 2025 research doesn't prove that cruise wastewater is universally harmful. What it does show is that treated cruise wastewater can still contain complex mixtures of chemicals that deserve further investigation.[13]
That's a much more useful conclusion.
The Air Pollution Problem
Have you ever thought about what comes out of the funnel?
Cruise ships produce carbon dioxide, nitrogen oxides, sulphur oxides and particulate matter. The impact can be particularly noticeable around ports. Research in Marseille has found associations between cruise-vessel arrivals and increases in short-term concentrations of pollutants including nitrogen dioxide and particulate matter.
But there is an important nuance here. Cruise ships aren't automatically the biggest source of pollution in every port. Road traffic, industry, other shipping and weather conditions all contribute. That matters because it is very easy to take one pollution statistic and turn it into:
"Cruise ships cause all the pollution."
They don't. But they can make a measurable contribution. And in some port environments, that contribution can be significant.
Recent research around Southampton has also identified ship-related ultrafine particles and metals including vanadium and nickel around the cruise terminal.[15] So the people affected aren't only the passengers. They're also the people who live and work around the ports.
The Industry is Not the Only Problem
This is where I think the conversation about cruise tourism needs to become more honest. Cruise ships are not uniquely responsible for ocean pollution. Shipping is only one contributor to underwater noise. Climate change is being driven by far more than cruise tourism. And coral reefs are under pressure from warming oceans, pollution, coastal development, overfishing and many other human activities.
My own research into ocean pollution made that interconnectedness particularly clear.
Climate change, chemical pollution, plastic pollution and physical disturbance don't happen independently. They can compound the pressure already being placed on marine ecosystems. So I don't think the answer is to pretend cruise ships are the single environmental villain.
They're not.
They're one part of a much bigger problem. However they are a problem that could be easily avoided if people no longer took cruise holidays.
The Industry is Growing
And this is where the sustainability argument becomes difficult. If an industry becomes more efficient but simultaneously becomes much larger, improvements at the individual-ship level don't necessarily mean that the total environmental footprint is falling. That's why I think the difference between efficiency and sustainability is so important.
A new ship might use less fuel per passenger than an older ship. A wastewater system might remove more pollutants. A slower vessel might produce less underwater noise.
Those are all positive developments.
But none of them, on their own, answers the bigger question:
Is the cruise industry as a whole becoming less damaging as it grows?
CLIA reported approximately 34.6 million cruise passengers in 2024, demonstrating the enormous scale of the industry.[16]
The industry is also continuing to invest in new ships and infrastructure. That doesn't automatically mean environmental impacts are increasing. But it does mean we need to look at the total picture rather than assuming that greater efficiency automatically equals sustainability.
But Cruises Bring Money
They absolutely do. According to CLIA and Oxford Economics, the cruise industry generated approximately $198.8 billion in global economic output and supported around 1.8 million jobs in 2024.[1]
Those figures shouldn't be ignored.
Cruise tourism provides employment, creates demand for local services and brings visitors to destinations around the world. Research into cruise destinations also recognises the economic benefits that cruise passengers can provide to local businesses and economies.[2]
But economic value doesn't automatically equal sustainability.
A cruise passenger might spend money ashore. But they also sleep on the ship, eat on the ship, use the ship's facilities and are transported between destinations by the ship.
Compare that with staying in a destination for several nights. You might use a locally owned hotel. Eat in independent restaurants. Hire a local guide. Use local transport. Spend money in shops. The economic model is different.
And I think where the money goes deserves just as much attention as how much money tourism generates.
So, can cruising ever be sustainable?
In my own opinion, No. But the research doesn't support such a simplistic conclusion.
There are genuine improvements being made. Advanced wastewater treatment is expanding. Shore power can reduce emissions while compatible ships are in port. Speed reductions can reduce fuel consumption and underwater noise. Better routing and scheduling can reduce unnecessary fuel use. Alternative fuels may eventually reduce certain emissions, although they come with their own challenges.
There are plenty of things the industry can do better. And those improvements matter.
But I think there is a bigger question underneath all of this.
Is making cruise tourism less harmful the same as making it sustainable?
I'm not sure it is.
What I choose to do
For me, this isn't about telling everyone that they're a terrible person if they take a cruise.
Travel has an impact.
Flying has an impact.
Driving has an impact.
Hotels have an impact.
Diving has an impact.
Even wildlife tourism, when done badly, can cause enormous damage.
There is no completely impact-free holiday.
What we can do is think more carefully about the impact we choose.
Personally, I'd rather spend my money in ways that directly support the places I'm visiting. Stay longer. Eat locally. Use local guides. Support independent businesses. Dive with responsible local operators. Choose wildlife experiences that put the animals first. And choose tourism that gives communities a reason to protect the environment people have travelled so far to experience.
Because if I'm travelling somewhere specifically because I want to see its reefs, wildlife, forests, beaches or marine life, I don't want my tourism to contribute to destroying the very thing I've gone there to see.
The Uncomfortable Question
Cruise tourism is changing. The technology is changing. The regulations are changing. The ships are changing. But the scale of the industry is changing too. And I think that's the part we need to keep talking about.
Because there is a huge difference between saying:
"This cruise ship is more environmentally efficient than the previous generation."
and saying:
"Cruise tourism is sustainable."
The first can be demonstrated. The second is much harder to prove.
I'm not against progress. I'm not against people enjoying cruises. I'm against pretending that progress means the problem has disappeared.
Because if an industry sells us the world's most beautiful places as a holiday...
shouldn't it be helping protect them too?
References
[1] Cruise Lines International Association & Oxford Economics (2026). Contribution of Cruise Tourism to the Global Economy 2024.
[2] Lloret, J., Carreño, A., Carić, H., San, J. & Fleming, L. E. (2021). Environmental and human health impacts of cruise tourism: A review. Marine Pollution Bulletin, 173, 112979. https://doi.org/10.1016/j.marpolbul.2021.112979
[3] Hoarau-Heemstra, H. et al. (2023). Cruise tourism destinations: Practices, consequences and the road to sustainability. Journal of Destination Marketing & Management, 30, 100820.
[4] U.S. Environmental Protection Agency. Cruise Ship Discharges and Studies.
[5] Transport & Environment (2026). Floating hotels.
[6] Chen, Q. et al. (2024). Using a bottom-up method to assess cruise ship activity impacts on emissions during 2019-2020 in China. Heliyon, 10(5), e27101.
[7] National Park Service. Glacier Bay underwater acoustic monitoring and cruise-ship noise research.
[8] NOAA / Alaska reporting (2026). Investigation into the fin whale found on the bow of Ovation of the Seas.
[9] Smith, S. H. (1988). Cruise ships: A serious threat to coral reefs and associated organisms. Ocean & Shoreline Management, 11(3), 231-248.
[10] Small, M. & Oxenford, H. A. (2022). Impacts of cruise ship anchoring during COVID-19: Management failures and lessons learnt. Ocean & Coastal Management, 229, 106332.
[11] Lester, S. E., White, C., Mayall, K. & Walter, R. K. (2016). Environmental and economic implications of alternative cruise ship pathways in Bermuda. Ocean & Coastal Management, 132, 70-79.
[12] Korbee, D., Mol, A. P. J. & van Tatenhove, J. P. M. (2015). Ecological considerations in constructing marine infrastructure: The Falmouth cruise terminal development, Jamaica. Marine Policy, 56, 23-32.
[13] van der Schyff, V. et al. (2025). Occurrence of Pharmaceuticals and Other Anthropogenic Compounds in the Wastewater Effluent of Arctic Expedition Cruise Ships. Environmental Science & Technology Letters, 12(5), 648-654.
[14] Cruise Lines International Association (2025). Protecting Our Oceans: Clean Water Cruise Ship Practices.
[15] University of Southampton (2026). Research into ship-related ultrafine particulate pollution around Southampton's cruise terminal.
[16] Cruise Lines International Association (2025). 2025 State of the Cruise Industry Report.
Written by Rebecca Allan