Insights · Data · Largest cruise ships
Two ships share the title of largest cruise ship afloat — Icon of the Seas and Star of the Seas, each measuring 248,663 gross tons. The figure is enormous, but it is a measure of volume, not weight, and that distinction explains the whole table.
Ask which cruise ship is the largest in the world and the honest answer, as of 2026, is that there are two. Icon of the Seas and Star of the Seas, sister ships in Royal Caribbean's Icon class, are the joint-largest cruise ships afloat by gross tonnage, each measuring 248,663 GT. They are built to the same design, in the same yard, to the same dimensions — so the record is genuinely shared rather than held by a single hull.
That headline number rewards a moment of unpacking, because gross tonnage is one of the most misread figures in shipping. It does not tell you how heavy the vessel is. It tells you how much enclosed space she encloses — and that is the key to why a cruise ship, rather than a supertanker, sits at the top of this particular table.
There is no single way to size a ship, and the right yardstick depends on what the ship is for. For cruise vessels the convention is gross tonnage (GT) — a dimensionless figure derived from the total enclosed volume of the ship under the 1969 International Convention on Tonnage Measurement of Ships. A bigger superstructure, more decks and more enclosed public space all push GT up. Weight does not enter the calculation at all.
This matters because the alternative measure, deadweight tonnage (DWT), captures something quite different: the mass of cargo, fuel, stores and crew a ship can carry. A loaded crude-oil tanker can run to 300,000 DWT or more, yet record a modest gross tonnage, because oil is dense and the hull is mostly tank. A cruise ship is the mirror image — vast volume, very little carried weight. If you only ever saw the deadweight tables you would conclude cruise ships were small. They are not; they are simply measured against the wrong ruler. For the full distinction, see our note on gross tonnage vs deadweight.
Icon of the Seas was inaugurated in January 2024, built at the Meyer Turku yard in Turku, Finland. She runs to around 365 metres in length over 20 decks, carries roughly 5,610 passengers at double occupancy — over 7,000 at full capacity — and is operated by a crew of about 2,350. At 248,663 GT she set the record on delivery.
Star of the Seas, the second ship of the class, made her maiden voyage on 31 August 2025 from Port Canaveral in Florida. Built to the identical Icon-class design, she matches her sister exactly at 248,663 GT — which is why the two now hold the title jointly rather than one displacing the other.
| Vessel | Gross tonnage | Length | Entered service |
|---|---|---|---|
| Icon of the Seas | 248,663 GT | ~365 m | Jan 2024 |
| Star of the Seas | 248,663 GT | ~365 m | Aug 2025 |
The Icon class overtook the earlier Oasis class — the ships that had held the crown for more than a decade — as the largest cruise vessels by gross tonnage. The Oasis-class ships remain among the very largest afloat, but the Icon design pushed the ceiling higher.
The reason is structural, in the most literal sense. A modern cruise ship is essentially a floating building: a dozen or more passenger decks, atria several storeys tall, theatres, restaurants, cabins by the thousand and entire enclosed promenades. Every cubic metre of that enclosed superstructure counts towards gross tonnage. A bulk carrier or a tanker of comparable length carries its load in open holds or in tanks low in the hull, with a tall but narrow accommodation block aft — far less enclosed volume, far lower GT.
Gross tonnage measures the space a ship encloses, not the weight she carries. That single convention is why a cruise ship tops the size tables while a supertanker tops the cargo tables. International Convention on Tonnage Measurement of Ships, 1969
So the "largest cruise ship" and the "largest ship" are answers to different questions. By gross tonnage, cruise ships lead. By deadweight, the ultra-large crude carriers lead. By length, container ships such as those covered in our guide to ship types push past 400 metres. None of these is wrong; each simply measures a different thing. If you are comparing vessels, the first discipline is to be sure you are comparing the same metric.
Every figure in this article is the kind of fact a vessel registry exists to hold. On Marifest, each cruise ship has its own file keyed to a permanent IMO number, listing gross tonnage, length, beam, year built, flag and registered owner. That is what lets you confirm a GT figure rather than take it on trust, and what lets you line two ships up side by side on the same measure.
To see the Icon class for yourself, browse the passenger fleet in the Marifest registry → and open the file for Icon of the Seas or Star of the Seas. You can also work from the operator side through cruise lines, which groups every vessel under the company that runs it, or check any term you meet along the way in the maritime glossary. The registry is free to search across more than 97,000 vessels — passenger ships, tankers, bulkers and the rest — so the cruise giants sit in the same dataset as everything else that floats.
How Marifest uses it
Marifest holds each cruise ship as a structured record — gross tonnage, dimensions, flag, owner and builder — so a headline figure like 248,663 GT can be checked, compared and traced rather than simply repeated.
Each vessel file carries its GT figure alongside length and beam, so you can confirm the 248,663 GT record and put two cruise ships on the same measure.
Filter the registry to passenger vessels and read the file on Icon of the Seas, Star of the Seas or any of the Oasis-class ships behind them.
Every cruise ship is tied to its registered owner and to the cruise line that runs it, so the fleet behind a brand is traceable hull by hull.
Each record shows flag state and sanctions standing, so a cruise vessel is read against the same compliance data as the rest of the world fleet.