The world's largest cruise ship is set to set sail from Miami, Florida on its maiden voyage amid concerns over the ship's methane emissions.
The 365 m long (1,197 ft) Icon of the Seas has 20 decks and can carry a maximum of 7,600 passengers. It is owned by the Royal Caribbean Group.
The ship embarks on a seven-day tropical island cruise.
But environmentalists warn that ships powered by liquefied natural gas can leak harmful methane into the air.
“This is a step in the wrong direction,” Brian Comer, director of the International Council for Clean Transportation's (ICCT) marine program, was quoted as saying by Reuters news agency.
“We estimate that using LNG as marine fuel releases 120% more life-cycle greenhouse gas emissions than marine gas oil,” he said.
LNG burns more cleanly than traditional marine fuels such as fuel oil, but there is a risk of spillage.
A potent greenhouse gas, methane in the atmosphere traps 80 times more heat than carbon dioxide over 20 years. Reducing these emissions is considered critical to reducing global warming.
A Royal Caribbean spokesperson was quoted by the media as saying Icon of the Seas is 24% more energy efficient than the International Maritime Organization's requirements for modern ships. The company plans to introduce a net zero ship by 2035.
On Thursday, Argentina's World Cup-winning captain Lionel Messi, who currently plays for Inter Miami, took part in the ship's naming ceremony. He was seen placing the football on a specially constructed stand to induce the traditional “good luck” of breaking a bottle of champagne against the ship's bow.
Icon of Cheese cost $2bn (£1.6bn) to build. It now has seven swimming pools, six water slides and more than 40 restaurants, bars and lounges.