Whether it’s a family vacation, summer holiday, or tropical getaway, for many people “cruising” has always been marketed as a fun, family getaway. Taking a closer look into the cruise industry, behind the all-inclusive marketing strategies, impressive engineering, and price-gouging excursions, the environmental consequences of these ships can be revealed. The release of thousands of gallons of wastewater and millions of tons of CO2 emissions, along with organism and ecosystem impacts, are only the tip of the iceberg when addressing the issues that cruising creates in the world’s most intense vacation hotspots[1]Cruise ship blues: the underside of the cruise industry – ProQuest. https://www.proquest.com/openview/6cd86f2f432f435d9dd976fd874b2f9b/1?pq-origsite=gscholar&cbl=35934..
Wastewater
Consider the vast amount of people on board every cruise ship. It’s not unreasonable to assume that this would result in the creation of an enormous amount of waste and wastewater. One cruise ship on a 7-day excursion can create thousands of gallons of oily bilge water, sewage, solid waste, and gray water. The disposal of this waste is poorly regulated and is often released into the ocean. Although there is some structure in place to fine cruise companies for this illegal dumping of waste, proving it is difficult, and catching the ships in the act is even more so[2]Simonsen, M., Gössling, S. & Walnum, H. J. Cruise ship emissions in Norwegian waters: A geographical analysis. Journal of Transport Geography 78, 87–97 (2019).. The influx of this wastewater into ocean ecosystems not only increases the amount of oil and toxic chemicals in the water, but the mass amount of human waste within it disrupts nutrient balances and sediment microbiomes, producing another toxic and disruptive anthropogenic pollution to the ecosystem[3]Mearns, A. et al. Biological and ecological effects of wastewater discharges from cruise ships in Alaska. in Oceans 2003. Celebrating the Past … Teaming Toward the Future (IEEE Cat. … Continue reading.
CO2 Emissions

Figure 1: Cruise ship emissions[4]Infographic: Cruise Ships Are the Biggest Black Carbon Polluters. Statista Infographics https://www.statista.com/chart/27353/worst-black-carbon-polluters (2022)..
The shipping industry in total produces 2.9% of the world’s carbon dioxide output. Although that seems like a small percentage, it does equate roughly to just over 1 billion tons each year. Within the shipping industry, cruising emits the highest amount of CO2, largely because of the amenities added to the ship, such as heated pools. Although cruise ships make up only 1% of the global ship fleet, they are responsible for 6% of the world’s black carbon emissions[5] Infographic: Cruise Ships Are the Biggest Black Carbon Polluters. Statista Infographics https://www.statista.com/chart/27353/worst-black-carbon-polluters (2022).. Black carbon is a grimy, sticky soot that is released from engines and other systems burning carbon, and results in increased acidification of water bodies, and degradation of air quality. In addition, cruise ships release high levels of nitrogen oxides (NOX) and particulate matter (PM) into the atmosphere, even more so than planes! These substances are also toxic to humans, and their inhalation has been linked to health concerns such as bronchitis, asthma, and some types of pulmonary cancer[6]Callahan, J. What if I told you cruising is worse for the climate than flying? International Council on Clean Transportation https://theicct.org/marine-cruising-flying-may22/ (2022).[7]Black Carbon Research and Future Strategies: Reducing emissions, improving human health, and taking action on climate change.. Although visitors may not spend enough time on or around the ships to see any major impacts from these toxins, ship, and port workers exposed to these toxins at higher concentrations for longer, may[8]Cruise liners try to rewrite climate rules despite vows. AP NEWS https://apnews.com/article/politics-caribbean-air-pollution-439aa4e49d8cafbaa922a79652372e8a (2022).[9]Butt, N. The impact of cruise ship generated waste on home ports and ports of call: A study of Southampton. Marine Policy 31, 591–598 (2007)..
Wildlife and Habitat Impacts
Due to their size and abundance, cruise ships pose a considerable disturbance to wildlife and their ecosystems. For example, the breeding and molting season of harbor seals in Alaska overlaps with peak cruise ship season for the region. The seals, which spend most of their time relaxing or basking on floating ice chunks have had a measured decline in population stability due to the constant flow of ships through their habitat. Additionally, cruise ships have been found to create significant mental stressors for the seals. Studies done in Disenchantment Bay, Alaska found that seals were expressing behavior indicative of stress such as decreased basking time, and would flee the area when approached by a ship. This stress causes unnecessary expenditures of stored energy and impacts the growth and development of seal pups[10]Jansen, J. K., Boveng, P. L., Dahle, S. P. & Bengtson, J. L. Reaction of Harbor Seals to Cruise Ships. The Journal of Wildlife Management 74, 1186–1194 (2010).
Furthermore, cruise ships carry thousands of people to locations that are otherwise difficult to visit, or entirely unreachable. The transport and inflow of this many people disturb the function of different ecosystems. For example, remote beaches that may be used as nesting sites for sea turtles, or migration stops for sea birds become overcrowded, and can no longer be used as resting points[11]Steinhoff, N. Cruise ships posing risk to sea turtles, review finds. Oceanographic https://oceanographicmagazine.com/news/cruise-ships/ (2021).. For example, Olive Ridley turtles (Lepidochelys olivacea) commonly nest on Costa Rican beaches. A study in 2015 on the species revealed that the abundance of tourists present on these same beaches resulted in delayed and reduced egg-laying events. Some turtles were even observed to leave the site before completing their nesting process. Cruise ships also harm marine animals; in the late 90s and early 2000s, a long-term study revealed that 12.7% of ship strikes on whales were from cruise ships. The effects of cruise ships on wildlife can also be indirect, this can include the consumption of toxic, and or artificial items from these boats that can lead to poisoning and choking[12]Cruise ships can be wildly harmful to the surrounding environment • Earth.com. https://www.earth.com/news/cruise-ship-harm-environment/.
Collision with organisms or specific ecosystems is also a huge issue in cruising and the cruise industry. In 2017, a British cruise ship crashed into an Indonesian reef destroying 17,222 square feet of coral reef, and roughly $19 billion in damages. Despite a monetary value being applied to the reef, when we consider the ecological and environmental impacts and value of this loss, there is no easy way to undo the damage or restore the ecosystem to what it was[13]Cruise ships must be effectively regulated to minimize serious environment and health impact — ScienceDaily. https://www.sciencedaily.com/releases/2021/09/210928193815.htm.[14]The Impacts of Cruises on the Ocean: What Has COVID-19 Changed? https://www.americanbar.org/groups/environment_energy_resources/publications/mr/20220502-the-impacts-of-cruises-on-the-ocean/..
Finally, to accommodate the increasing size and number of cruise ships present in global port sites, dredging has been used to increase the number of passable waterways. Dredging is the practice of removing soils and sediments from the bottom of waterways to increase the depth of a canal or port to allow larger ships to pass[15]Walker, B., Gilliam, D., Dodge, R. & Walczak, J. Dredging and Shipping Impacts on Southeast Florida Coral Reefs. Marine & Environmental Sciences Faculty Proceedings, Presentations, Speeches, … Continue reading. The process not only destroys ecosystems in the immediate vicinity as they are dug up and torn apart, but the disruption of sediment results in a blanketing effect on nearby habitats often choking out coral reefs and seagrass beds. Dredging also increases turbidity (decreases water clarity) which can have lasting effects on the ability of marine plants and algae to complete photosynthesis[16]Jones, R., Bessell-Browne, P., Fisher, R., Klonowski, W. & Slivkoff, M. Assessing the impacts of sediments from dredging on corals. Marine Pollution Bulletin 102, 9–29 (2016).[17]Lester, S. E., White, C., Mayall, K. & Walter, R. K. Environmental and economic implications of alternative cruise ship pathways in Bermuda. Ocean & Coastal Management 132, 70–79 (2016)..
So, What Now?
The vast number of issues with the cruise industry may seem like a difficult problem to address and fix. However, the solutions are quite clear: most easily we can simply reduce the number of cruises taken, and focus on prioritizing more sustainable and eco-conscious travel options by researching the companies you purchase tickets from, or opting for reputable local options rather than large, global companies. Furthermore, putting pressure on cruise companies to significantly reform the actual structure, and mechanical processes of the ships to reduce waste output can provide significant support for the protection of marine ecosystems. Installing scrubbers and other carbon dioxide regulatory devices can help to minimize greenhouse gas input. Finally, reducing visitation to more fragile, or remote locations provides protection for these ecosystems and support for the organisms living within them[18]Pallis, A. A. & Vaggelas, G. K. Chapter 13 – Cruise Shipping and Green Ports: A Strategic Challenge. in Green Ports (eds. Bergqvist, R. & Monios, J.) 255–273 (Elsevier, 2019). … Continue reading.
Cruising is not an essential industry, and so there is no excuse to continue in its unsustainable, damaging nature. We are responsible for finding opportunities for recreational travel without causing significant environmental damage. So, if you’re craving a tropical getaway, consider a smaller, or local approach. Visit beaches, or islands independently or with a smaller group. Support local economies, and educate yourself on the environmental, and ecosystem structures within the area. Considering the threat to our oceans from pollution stemming from other industries, there is no excuse for us to make reckless contributions in the name of cruising.
References
↑1 | Cruise ship blues: the underside of the cruise industry – ProQuest. https://www.proquest.com/openview/6cd86f2f432f435d9dd976fd874b2f9b/1?pq-origsite=gscholar&cbl=35934. |
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↑2 | Simonsen, M., Gössling, S. & Walnum, H. J. Cruise ship emissions in Norwegian waters: A geographical analysis. Journal of Transport Geography 78, 87–97 (2019). |
↑3 | Mearns, A. et al. Biological and ecological effects of wastewater discharges from cruise ships in Alaska. in Oceans 2003. Celebrating the Past … Teaming Toward the Future (IEEE Cat. No.03CH37492) vol. 2 737-747 Vol.2 (2003). |
↑4 | Infographic: Cruise Ships Are the Biggest Black Carbon Polluters. Statista Infographics https://www.statista.com/chart/27353/worst-black-carbon-polluters (2022). |
↑5 | Infographic: Cruise Ships Are the Biggest Black Carbon Polluters. Statista Infographics https://www.statista.com/chart/27353/worst-black-carbon-polluters (2022). |
↑6 | Callahan, J. What if I told you cruising is worse for the climate than flying? International Council on Clean Transportation https://theicct.org/marine-cruising-flying-may22/ (2022). |
↑7 | Black Carbon Research and Future Strategies: Reducing emissions, improving human health, and taking action on climate change. |
↑8 | Cruise liners try to rewrite climate rules despite vows. AP NEWS https://apnews.com/article/politics-caribbean-air-pollution-439aa4e49d8cafbaa922a79652372e8a (2022). |
↑9 | Butt, N. The impact of cruise ship generated waste on home ports and ports of call: A study of Southampton. Marine Policy 31, 591–598 (2007). |
↑10 | Jansen, J. K., Boveng, P. L., Dahle, S. P. & Bengtson, J. L. Reaction of Harbor Seals to Cruise Ships. The Journal of Wildlife Management 74, 1186–1194 (2010 |
↑11 | Steinhoff, N. Cruise ships posing risk to sea turtles, review finds. Oceanographic https://oceanographicmagazine.com/news/cruise-ships/ (2021). |
↑12 | Cruise ships can be wildly harmful to the surrounding environment • Earth.com. https://www.earth.com/news/cruise-ship-harm-environment/ |
↑13 | Cruise ships must be effectively regulated to minimize serious environment and health impact — ScienceDaily. https://www.sciencedaily.com/releases/2021/09/210928193815.htm. |
↑14 | The Impacts of Cruises on the Ocean: What Has COVID-19 Changed? https://www.americanbar.org/groups/environment_energy_resources/publications/mr/20220502-the-impacts-of-cruises-on-the-ocean/. |
↑15 | Walker, B., Gilliam, D., Dodge, R. & Walczak, J. Dredging and Shipping Impacts on Southeast Florida Coral Reefs. Marine & Environmental Sciences Faculty Proceedings, Presentations, Speeches, Lectures (2012). |
↑16 | Jones, R., Bessell-Browne, P., Fisher, R., Klonowski, W. & Slivkoff, M. Assessing the impacts of sediments from dredging on corals. Marine Pollution Bulletin 102, 9–29 (2016). |
↑17 | Lester, S. E., White, C., Mayall, K. & Walter, R. K. Environmental and economic implications of alternative cruise ship pathways in Bermuda. Ocean & Coastal Management 132, 70–79 (2016). |
↑18 | Pallis, A. A. & Vaggelas, G. K. Chapter 13 – Cruise Shipping and Green Ports: A Strategic Challenge. in Green Ports (eds. Bergqvist, R. & Monios, J.) 255–273 (Elsevier, 2019). doi:10.1016/B978-0-12-814054-3.00013-X. |
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