The world's largest cruise ship, Icon of the Seas, sets sail on its maiden voyage from Miami

• Royal Caribbean's Icon of the Seas sailed today on a seven-day island hopping cruise in the Caribbean before returning to Miami
• Despite claims that the LNG used is better than traditional marine fuel, environmentalists believe the ship poses significant risks of methane emissions.
• Methane is a potent greenhouse gas and is the second largest contributor to global warming after carbon dioxide

The world's largest cruise ship has begun its seven-day maiden voyage from the Port of Miami, carrying nearly the population of a small town.

Royal Caribbean's Icon of the Seas sailed today on a seven-day island hopping cruise in the Caribbean before returning to Miami.

The ship costs $2 billion, extends approximately 1,200 feet (365 meters) from bow to stern, and consists of 20 decks, 2,350 crew and 2,805 luxury rooms, in addition to space for 7,600 passengers.

Apart from this, the ship also includes a 55-foot artificial waterfall, 40 dining venues and bars, seven swimming pools including a 40,000-gallon 'lagoon', 50 musicians and comedians as well as a 16-piece orchestra.

The ship is powered by “environmentally friendly liquefied natural gas”. according to ReutersRoyal Caribbean said the Icon is 24 percent more efficient when it comes to carbon emissions than the International Maritime Organization requires.

Royal Caribbean also said that every kilowatt used on the Icon of the Seas “is screened for energy efficiency and emissions reductions.”

But despite claims that the fuel is better than traditional marine fuel, environmentalists believe the ship poses significant risks of methane emissions.

According to the International Council on Clean Transportation, methane emissions from LNG-powered ships in the form of “methane slippage” contribute to climate change.

Methane slippages occur when ships like the Icon use low-compression dual-fuel engines that tend to leak methane into the atmosphere during the combustion process.

Brian Comer, ICCT Marine Program Manager to explain:'It's a step in the wrong direction.

“We estimate that using LNG as a marine fuel results in more than 120% greater life-cycle greenhouse gas emissions than marine gasoil.”

Cruise ship engines are estimated to emit 6.4 percent more methane on average, by 2024 research Funded by ICCT, which is higher than the IMO assumption of 3.5 percent.

Methane is a powerful greenhouse gas and is the second-largest contributor to global warming after carbon dioxide, according to NASA's Global Climate Change. website.

An estimated 60% of methane emissions today are the result of human activities.

But those concerns don't seem to be bothering the owners, as the ship is scheduled to sail year-round Caribbean itineraries from Miami, with itineraries featuring “perfect destinations” and stopping at an “award-winning private island” for Perfect Day at CocoCay in the Bahamas.

The ship was officially “christened” on Tuesday by the World Cup winner Lionel Messi And his teammates in the Inter Miami team.

Messi was the headline act at the event, placing a football atop a platform to “begin” the traditional breaking of a champagne bottle on the bow of the ship – which is supposed to bring good luck to the ship and its passengers.

The 36-year-old Argentine later described it as a “privilege”.

“It is a great honor for me and I know what this means for the city of Miami and the whole world,” Messi said in Spanish. “Therefore, I call this ship the Icon of the Seas.” God bless you and all the people who will be sailing with her.

“We've built the biggest, baddest ship on the planet,” added Michael Bailey, President and CEO of Royal Caribbean International. “It's really exciting when you introduce a new class of ship, but even more exciting is when it looks really good.”