At 600,000 tons and 243 feet wide, when the Prelude left its dry dock in South Korea after a year-long build, it unseated the Emma Maersk (1,302 feet) as the world’s largest ship. But calling it a ship is almost a misnomer. The Prelude is a floating liquefied natural gas (FLNG) facility that will be posted off the coast of Western Australia and will stay there for the next quarter-century.