The Brown Side of Cruising

Last year, the cruise ship industry released more than one billion gallons of untreated sewage into the world’s oceans [1]. That’s the equivalent of 19 backyard swimming pools full of human excretion – every day. And in International Waters, that’s perfectly legal.

cruiseMany nations take it upon themselves to restrict sewage dumping in their respective waters. For instance, US federal law prohibits dumping of untreated sewage within three miles of shore [2]. Beyond that point, ships are in International Waters and under no specific jurisdiction. MARPOL 73/78, the International Convention for the Prevention of Pollution from Ships, first sought to limit dumping of oils and hazardous wastes, though has since been amended to include sewage and plastic wastes. MARPOL now echoes US law banning untreated discharge within three miles of nearest land, though allows discharge further out, so long as the “Effluent does not produce visible floating solids nor cause discoloration of the surrounding water” [3]. Full MARPOL text available here.

It doesn’t take a scientist to recognize that the continued, large-volume release of raw sewage might negatively impact the world’s oceans. A 1990’s NOAA-commissioned study of a 106-mile “dump site” off the coast of New York confirmed the fears of ecologists worldwide. It was found that not only does the particulate matter released during deep-water dumping eventually reside on the ocean floor, but it causes a significant re-structuring of the deep-sea ecosystem for hundreds of miles around the dump site [4]. Bottom line, it’s bad – but with most ships registered under other flags and operating in International Waters, it’s also out of our direct control.

Thankfully, there is much power in consumer choice. Independent energy-starrating systems have proven to be a successful marketing tactic across many industries. An obvious driver of consumer choice, dozens of ratings – Energy Star, LEED, even “Dolphin Safe” tuna – have helped industries reach new customer bases by promoting long-term thinking and wholistic product awareness. Even Seattle Public Utilities has seen positive results, as customers reduce their respective energy usage 2-3% in response to stratification amongst their neighbors: a simple smiley or frowny face [5].


Therein lies the solution: a rating system. It would seem a safe assumption that much of the American population would take issue with promoting widespread fouling of the oceans. Therefore, if we create a widely-applicable and recognizable system to stratify cruise lines according to their respective environmental impacts, we can make a significant impact on the industry as a whole. While cruising is an international industry worth over $37 billion, nearly half of the passengers are US citizens [6]. The impact of a successful rating system certainly won’t be limited to American travelers, but even starting at a domestic level, we can make a huge difference.


[1] Keever, Marcie. “Cruise Ship Sewage,” The New York Times. 29 June 2016. [Online]. Available: [Accessed 21 February 2017].
[2] “Regulation of Ship Pollution in the United States,” Wikipedia. 21 February 2017. [Online]. Available: [Accessed 21 February 2017].
[3] “MARPOL 73/78,” Wikipedia. 21 February 2017. [Online]. Available: [Accessed 21 February 2017].
[4] Collie, Marsha and Russo, Julie. “Deep Sea Biodiversity and the Impacts of Ocean Dumping,” NOAA Undersea Research Program. 30 June 2000. [Online]. Available: [Accessed: 21 February 2017].
[5] Sutter, John. “Energy Efficiency – With a Digital Smile,” CNN. 3 December 2010. [Online]. Available: [Accessed 21 February 2017].
[6] Kennedy, Sarah. “2016 Cruise Industry Outlook,” CLIA. 2016. [Online]. Available: [Accessed 21 February 2017].

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