The world's largest cruise ship has set sail from Miami, Florida, on its maiden voyage, amid concerns about the vessel's methane emissions, APA reports citing BBC.
The 365m-long (1,197 ft) Icon of the Seas has 20 decks and can house a maximum of 7,600 passengers. It is owned by Royal Caribbean Group.
The vessel is going on a seven-day island-hopping voyage in the tropics.
But environmentalists warn that the liquefied natural gas-powered ship will leak harmful methane into the air.
"It's a step in the wrong direction," Bryan Comer, director of the Marine Programme at the International Council on Clean Transportation (ICCT), was quoted as saying by Reuters news agency.
"We would estimate that using LNG as a marine fuel emits over 120% more life-cycle greenhouse gas emissions than marine gas oil," he said.
Earlier this week, the ICCT released a report, arguing that methane emissions from LNG-fuelled ships were higher than current regulations assumed.
LNG burns more cleanly than traditional marine fuels such as fuel oil, but there is a risk of leakage.