When it comes to ranking the largest cruise ships in the world, size is measured in gross tonnage (GT), not gross register tonnage (GRT), an older measurement system phased out decades ago under international maritime convention and no longer used for any vessel built today. It’s also worth clearing up a common misconception: gross tonnage has nothing to do with weight. GT is a measure of a ship’s total enclosed volume, calculated from the interior cubic capacity of the vessel, not how many tons it weighs. A cruise ship’s actual weight is expressed separately as displacement tonnage, a figure you’ll rarely see used anywhere in the cruise industry. Every “largest cruise ships in the world” list you come across, including this one, is really ranking ships by how much interior volume they contain, not by mass.

Scroll through the list below and one thing becomes obvious fast: this is largely a Royal Caribbean conversation. Of the ten largest cruise ships sailing today, nine belong to Royal Caribbean International, spanning both the Icon Class and the Oasis Class. The lone outlier is MSC Cruises’ MSC World America, which just barely cracks the top 10. That kind of dominance isn’t an accident. Royal Caribbean has spent close to two decades pushing the upper limits of cruise ship design, from the original Oasis of the Seas in 2009 through today’s Icon Class ships, and no other cruise line has managed to keep pace at the very top end of the size spectrum.

#1

Legend of the Seas

Icon Class | 248,663gt | 1,197.83ft LOA | 159ft Beam

Legend of the Seas is the third and newest ship in the Icon Class, debuting in the summer of 2026. Like her sisters, she ties for the largest cruise ship in the world by gross tonnage, and she brings her own new entertainment lineup, including a Broadway-style production of Charlie and the Chocolate Factory.

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#2

Star of the Seas

Icon Class | 248,663gt | 1,196.9ft LOA | 159ft Beam

Star of the Seas is the second ship in Royal Caribbean’s Icon Class, joining her sister Icon of the Seas in August 2025. She shares nearly identical dimensions with Icon, tying her for the top spot on this list, with refinements made to venue layouts and passenger flow based on lessons learned from Icon’s first year in service.

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#3

Icon of the Seas

Icon Class | 248,663gt | 1,196ft LOA | 160ft Beam

The Icon of the Seas remains the benchmark for what a modern mega-ship can be. The first of Royal Caribbean’s Icon Class entered service in January 2024, and even with two sister ships now in the fleet, she still ties for the title of the largest cruise ship in the world by gross tonnage.

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#4

Utopia of the Seas

Oasis-Plus Class | 236,473gt | 1,188ft LOA | 156ft Beam

Utopia of the Seas debuted in July 2024 as the sixth ship in Royal Caribbean’s Oasis-class lineage and the first in the class powered by liquefied natural gas. Built primarily for short getaway cruises out of Port Canaveral, her gross tonnage edges out fleetmate Wonder of the Seas.

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#5

Wonder of the Seas

Oasis-plus Class | 235,600gt | 1,187ft LOA | 154ft Beam

The now fifth largest cruise ship in the world is Royal Caribbean’s Wonder of the Seas. This 5,700 passenger ship, at double occupancy, was the first in the next iteration of the Oasis-class of vessels, later joined by her sister Utopia of the Seas.

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#6

Symphony of the Seas

Oasis Class | 228,081gt | 1,184ft LOA

The 2018 built vessel is the largest in the original run of Oasis-class vessels for cruise giant Royal Caribbean. While she’s identical to the Harmony of the Seas (#7 in our list) she’s only fractionally larger, based on tonnage, so she goes above Harmony of the Seas.

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#7

Harmony of the Seas

Oasis Class | 226,963gt | 1,188ft LOA

Harmony of the Seas launched in 2016 from STX France and sails for Royal Caribbean. The ship is a slight enhancement of the Oasis-class of vessels. The original two listed below were built in Finland. When it came time to order the next pair of vessels, Royal Caribbean opted to go with a different yard. This allowed them to make some improvements to the two new vessels. This essentially let the Harmony and Symphony reside in their own class of ships.

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#8

Oasis of the Seas

Oasis Class | 226,838gt | 1,181ft LOA

Oasis of the Seas made history in 2009 as the first ship in the Oasis class and, at the time, the largest cruise ship ever built. More than a decade and a half later she’s still sailing strong for Royal Caribbean, now out of Port Canaveral. After several refits, and new additions added to the ship, mainly additional cabins added above the bridge, this increased her overall gross tonnage from her as-delivered numbers.

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#9

Allure of the Seas

Oasis Class | 226,637gt | 1,181ft LOA

Allure of the Seas entered service in 2010 as the second ship in the original Oasis class, essentially a sister ship to Oasis of the Seas. She spent years sailing out of Florida with intermittent summer seasons in Europe.

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#10

MSC World America

World Class | 216,638gt | 1,092ft LOA | 154ft Beam

MSC World America is the only non-Royal Caribbean ship to crack the top 10, and the largest vessel in MSC Cruises’ fleet. She debuted in 2025 as the second ship in the World Class, edging out sister ship MSC World Europa in gross tonnage and continuing MSC’s push toward LNG-powered propulsion.

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#11

MSC World Europa

World Class | 215,863gt | 1,093ft LOA

The MSC World Europa is a cutting-edge cruise ship belonging to MSC Cruises. Launched in 2022, she has a capacity for up to 6,850 passengers and a crew of approximately 2,180, it features 19 passenger decks. The ship boasts state-of-the-art facilities, including diverse dining venues, entertainment options such as theaters and a multimedia lounge, and innovative attractions like the “MSC Starship Club” with its humanoid robotic bartender. Advanced navigation systems and sustainable features underline its commitment to modern maritime technology and eco-friendly operations.

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#12

Disney Adventure

Global Class | 208,108gt | 1,124ft LOA | 152ft Beam

Disney Adventure is Disney Cruise Line’s eighth ship and its largest yet, entering service in March 2026 as the line’s first vessel based outside the United States, homeported in Singapore. Originally begun as the ill-fated Global Dream for Genting Hong Kong before Disney acquired the unfinished hull, she carries up to 6,700 passengers across seven themed lands, including a dedicated Marvel zone with the longest rollercoaster at sea.

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#13

Costa Toscana

Excel Class | 186,364gt | 1,106ft LOA

The Costa Toscana is a remarkable cruise ship operated by Costa Cruises. Debuted in 2021, it spans about 337 meters in length and has a gross tonnage of around 185,000. Designed to accommodate up to 5,224 passengers and with a crew capacity of approximately 1,646, the ship encompasses 20 passenger decks. Onboard, passengers can enjoy a range of amenities including diverse dining options, entertainment venues like theaters and a water park.

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#14

Arvia

Excel Class | 185,581gt | 1,128ft LOA

The P&O ship Arvia was launched in 2022. With ample space for up to 5,200 passengers and a crew of about 1,700, the ship encompasses 17 decks, featuring an array of amenities such as diverse dining options, entertainment venues including theaters and a SkyDome, and innovative attractions like the Altitude Skywalk and Ocean Studios.

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#15

Costa Smeralda

Excel Class | 185,010gt | 1,106ft LOA

Costa Smeralda is operated by Costa Cruises. Launched in 2019, the ship welcomes up to 6,554 passengers and accompanied by a crew of about 1,646, the ship comprises 20 passenger decks. Onboard, passengers can enjoy a variety of amenities including diverse dining options, entertainment venues like theaters and a lavish spa, and unique attractions such as the Colosseo, an area dedicated to entertainment and events.

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