Gross tonnage is not weight. It is enclosed volume, and it is the only number the cruise industry agrees to be ranked by, which is why a ship that displaces less water than a container vessel can still be called the largest thing ever put to sea for fun. By that measure the top of the table now belongs to three identical Royal Caribbean hulls at 248,663 tons apiece, and the newest of them only started sailing in July 2026. Below them the order gets messy fast, because operators refit their ships and the numbers move. Oasis of the Seas launched at 225,282 tons and now sits at 226,838. Allure gained tonnage in a 2025 overhaul. Every figure here was checked against the operator spec sheet, and where the operator and the reference books disagree, the operator wins and the number is prefixed with about. Twenty seven ships, largest first, with the comparison hulls and the one still under construction at the end.
Icon of the Seas, 248,663 GT
The record still belongs to Royal Caribbean’s first Icon class hull, handed over by Meyer Turku in Finland and sent out of PortMiami on her maiden voyage on 27 January 2024. She runs 364.75 metres from bow to stern, sleeps 5,610 guests at double occupancy and takes 7,600 when every upper berth is folded down, with 2,350 crew underneath that. The number that matters, 248,663 gross tons, measures enclosed volume rather than mass, and it is the target every rival naval architect now works against. What the tonnage buys is Category 6, a six slide waterpark stacked across the aft decks, seven pools, eight distinct neighbourhoods and a suspended park planted with living trees. No other vessel afloat pairs that footprint with that passenger count.