This question is one of the most frequently asked to anyone who works in the world of shipping, and unfortunately there is no easy answer. It really depends on what you mean by biggest.
THE LONGEST
Name: “Knock Nevis”*
Type: Supertanker
Length: 458 metres
THE WIDEST
Name: “USS Nimitz”
Type: Aircraft Carrier
Width (Beam): 77 metres
THE HIGHEST GROSS TONNAGE (GT)
Name: “Batillus”
Type: Supertanker
GT: 275,276 tons
THE MOST PEOPLE ONBOARD
Name: “Oasis of the Seas”
Type: Cruise Ship
Capacity: 6,296 people (passengers and crew)
* The “Knock Nevis” has now reached the end of its useful life and has been sold to a firm of Indian shipbreakers. People often wonder why, in an industry of economies of scale, more supertankers of this size and larger have not been built. Well we have to remember that the Knock Nevis’ size also caused its owners a lot of logistical problems; its huge size required a draft (a water depth) of over 80 feet, meaning some of the world’s main shipping routes, like the Suez and Panama Canals and the English Channel, were no-go areas for the ship.