Cruise tourism: The dark side of a growing industry

Global cruise tourism is growing rapidly. Passenger numbers are expected to reach 33.7 million this year. However, this growth, which has regained momentum following the Covid-19 pandemic, comes with serious environmental impacts.

Wastewater and marine pollution

According to the U.S. Environmental Protection Agency, a 3,000-passenger cruise ship produces 176,000 gallons of wastewater per week. This compares to more than 1 billion gallons of wastewater annually for the industry as a whole—the equivalent of 1,515 Olympic-sized pools.

While modern ships have wastewater treatment systems before discharge, contaminants such as heavy metals, nutrients, and non-biodegradable organic chemicals can still leach into the water after treatment. According to a report by Friends of the Earth, none of the major cruise lines publicly disclose the performance of their advanced wastewater treatment systems.

According to Earth.org , the marine environment is vulnerable to pollution from ships, including black water ( toilet waste) and gray water (sink, shower, laundry, and kitchen waste). This waste can lead to harmful algal blooms that reduce oxygen levels, disrupt plankton photosynthesis and metabolism, and inhibit the growth of marine life. Ballast and bilge water also threaten ecosystems with toxic compounds and petroleum derivatives.

Air pollution and emissions

According to Transport & Environment data , 214 cruise ships operating in European ports in 2022 emitted 509 tons of sulfur oxides, 19,125 tons of nitrogen oxides, and 448 tons of PM2.5. While the International Maritime Organization's global limit on sulfur in ship fuels, introduced in 2020, aims to reduce emissions, cruise ships still emit more sulfur than all cars in Europe.

The industry is shifting to using liquefied natural gas (LNG) instead of diesel. While LNG reduces carbon dioxide and sulfur emissions, it also contains high levels of methane. Methane has been a greenhouse gas 80 times more potent than carbon dioxide over the past 20 years. Experts emphasize that the industry needs to shift to truly clean fuels like green hydrogen.

Noise and solid waste problems

Underwater noise generated by cruise ships negatively impacts navigation, communication, and feeding behaviors of many species, especially marine mammals. Noise pollution disrupts the ecological balance, particularly in protected areas where sensitive species live.

In addition, a weeklong cruise creates approximately 50 tons of solid waste. Cruise ships account for 24% of the solid waste generated by global maritime transport. Plastic waste poses long-term risks of poisoning and death to marine life.

“Green” discussions in the sector

In Friends of the Earth 's air pollution assessment, Disney Cruise Lines received a C+, Royal Caribbean a D-, and Cunard Cruise Line an F. Only Norway's Hurtigruten expedition ship achieved an A.

Last year, the Dutch Advertising Board deemed MSC Cruises' ads promoting LNG as a "sustainable fuel" and claiming progress toward its 2050 net-zero target "misleading." Environmental groups say the industry spends billions on green image campaigns while lobbying against environmental regulations.