World's Largest Cruise Ship Sets Sail And Environmentalists Are Not Happy

The Icon Of The Seas has been described as everything from "human lasagne" to "a step in the wrong direction".


Tom Hale


Tom Hale

Senior Journalist

Tom is a writer in London with a Master's degree in Journalism whose editorial work covers anything from health and the environment to technology and archaeology.

Senior Journalist

Edited by Laura Simmons
Laura Simmons - Editor and Staff Writer

Laura Simmons

Editor and Staff Writer

Laura is an editor and staff writer at IFLScience. She obtained her Master's in Experimental Neuroscience from Imperial College London.

Royal Caribbean International’s "Icon of the Seas" arrived in Miami for the first time ahead of its official debut on January 27, 2024.

Royal Caribbean International’s Icon of the Seas arrived in Miami for the first time ahead of its official debut on January 27, 2024.

Image credit: Royal Caribbean

The world's largest cruise ship – the Icon of the Seas – set sail from Miami on its maiden voyage last weekend. Not everyone was celebrating the departure of the all-singing, all-dancing colossus, however. Although it's been pitched as a climate-friendly vessel, numerous environmental groups have raised concerns about the huge amounts of methane that will be coughed up by its engines. 

Owned by Royal Caribbean Group, the Icon of the Seas is 365 meters long (1,197 feet), features 20 decks, and can hold a maximum of 7,600 passengers. 


It’s essentially a floating water park, equipped with seven different pools and six record-breaking water slides. On top of that, there are dozens of entertainment venues, bars, and restaurants.

All of this commotion requires a heap of energy. The floating city is powered by liquefied natural gas (LNG), which Royal Caribbean dubs “the cleanest-burning marine fuel”. While LNG engines are more efficient and emit less carbon dioxide (CO2) than conventional maritime fuels, they still pump out substantial amounts of methane.

Methane is the second most abundant greenhouse gas produced by human activities and it's especially problematic because it traps substantially more heat than CO2. Fortunately, it does have a shorter atmospheric lifetime than CO2, persisting for just over a decade compared with centuries.

The Icon of the Sea has six record-breaking water slides, plus more than 40 restaurants, bars and entertainment venues.
The Icon of the Seas has six record-breaking water slides, plus more than 40 restaurants, bars, and entertainment venues.
Image credit: Royal Caribbean

The problem with LNG engines is “methane slip”, a process in which unburned fuel that is not fully combusted leaks into the surrounding atmosphere. Here, it will rise into Earth’s atmosphere to help trap heat, thereby increasing the temperature of the planet. 


Just last week, a new report by the International Council on Clean Transportation (ICCT) concluded that LNG engines likely produce significantly more methane than most international regulators assume. They also argue that the methane-producing potential of LNG could be enough to scupper current plans to decarbonize the shipping industry.

"It's a step in the wrong direction," said Bryan Comer, director of the Marine Programme at the ICCT, according to Reuters news agency.

"We would estimate that using LNG as a marine fuel emits over 120 percent more life-cycle greenhouse gas emissions than marine gas oil," he added.

The Icon of the Seas cruise ship, made by Royal Caribbean, in Miami Florida.
The Icon of the Seas is powered by LNG, which Royal Caribbean dubs “the cleanest-burning marine fuel”.
Image credit: Royal Caribbean

Environmental groups also denounced the maiden voyage of the Icon of the Seas, reaffirming the idea that the cruise industry is not taking the necessary steps to cut their emissions.


“The ships are getting bigger and bigger and that is the wrong direction for the cruise industry to be going. If you were really thinking about sustainability and not your bottom line, you would not be building a cruise ship with a capacity of nearly 10,000 people,” Marcie Keever, director of the Oceans and Vessels Program at the environmental organization Friends of the Earth, told the New York Times.

For their part, Royal Caribbean Group says they view as LNG as a transitional fuel and plan to introduce a net-zero ship by 2035 to achieve net-zero emissions by 2050.

Despite growing awareness of greenhouse gases and climate change, the cruise industry is booming. The cruise tourism market is set to surge by $21.02 billion from 2022 to 2027 with an annual growth rate of 11.4 percent. 

While many have criticized the Icon of the Seas for being a “step in the wrong direction,” it looks like many people are eager to join along on the journey regardless. 


  • tag
  • greenhouse gas emissions,

  • shipping,

  • methane,

  • environment,

  • Engineering,

  • miami,

  • tourism,

  • cruise ships,

  • liquefied natural gas