Icon of the Seas: World's largest cruise ship sets sail

The world's largest cruise ship has begun its maiden voyage.

Royal Caribbean's Icon of the Seas set sail from Miami in Florida on Saturday with a capacity for up to 7,600 passengers and 2,350 crew members.

The ship runs nearly 1,200ft (365m) from bow to stern and is divided into eight neighbourhoods across 20 decks.

The vessel features six waterslides, seven swimming pools, an ice skating rink, a theatre and more than 40 restaurants, bars and lounges.

It has begun its first seven-day island-hopping voyage in the tropics.

Icon of the Seas was officially christened on Tuesday with the help of football legend Lionel Messi and his Inter Miami teammates.

The ship is powered by six dual-fuel engines, which can be powered by liquefied natural gas (LNG), a fuel alternative the Cruise Lines International Association says reduces sulfur and greenhouse gas emissions.

However, environmental groups have raised concerns LNG-powered ships increase harmful methane emissions.

"It's a step in the wrong direction," Bryan Comer, director of the Marine Program at the International Council on Clean Transportation (ICCT), told Reuters.

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

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Methane is 80 times worse over 20 years than carbon dioxide in terms of warming effects. Cutting the emissions is seen as key to keeping down global temperature warming.

Royal Caribbean says every kilowatt used on the Icon of the Seas "is scrutinized for energy efficiencies and emission reductions."