The biggest ship I have ever been on was an oil tanker. I guess that doesn't qualify as a cargo ship.
The oil tanker Jahre Viking was the largest ship afloat in 1999. She is 458 meters [1,503 feet long] long, with a beam of 69 meters [226 feet]. The hull extends 25 meters below the water-line. When it is fully loaded with
[COLOR=#3976C1 ! important][COLOR=#3976C1 ! important]crude [COLOR=#3976C1 ! important]oil[/color][/color][/color], she has a gross tonnage of 565,000 tons.
Actually, the Maersk is the largest current cargo ship. There were 4 larger ones. 3 have been scrapped and one has FSO status. It is the largest cargo ship ever built, the Knock Nevis.
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