World's Largest Ship Launches for First Time

Wired:

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.
As an FLNG plant, the Prelude handles everything involved in capturing, processing, and storing liquid natural gas, sucking the stuff from deep within the Earth and refining 3.9 million tons each year before it’s offloaded onto smaller ships that bring it back to the mainland.
Since the Prelude has to process and hold 175 Olympic swimming pools’ worth of the liquid natural gas year-round, it has to withstand anything Mother Nature sends its way. For that, there’s a 305-foot-tall turret that runs through the ship and into the seafloor, keeping the Prelude anchored and allowing it to slowly pivot to the direction of the wind. Between the moorings, the turret, and the three 6,700-horsepower engines, the ship can handle a category 5 hurricane.
The Prelude is set to launch in 2017, and will settle into its new home 300 miles north-east of Broome, Western Australia through 2042.

Yeah, it's bigger than this ship.  Here's some video explanation: