Biggest Cruise Ships in the World, Ranked by Size

Every one of the 10 largest cruise ships afloat belongs to one of two Royal Caribbean hull designs, plus a single MSC ship. The table below ranks them by gross tonnage (GT), the standard measure of a ship's enclosed volume and the figure cruise lines themselves use when they call a ship the "world's largest."

Gross tonnage, cruise line and year entered service. Icon of the Seas, Star of the Seas and Legend of the Seas are tied for first at 248,663 GT.
Rank Ship Cruise line Gross tonnage Entered service
1 Icon of the Seas Royal Caribbean 248,663 GT 2024
2 Star of the Seas Royal Caribbean 248,663 GT 2025
3 Legend of the Seas Royal Caribbean 248,663 GT 2026
4 Utopia of the Seas Royal Caribbean 236,860 GT 2024
5 Wonder of the Seas Royal Caribbean 236,857 GT 2022
6 Symphony of the Seas Royal Caribbean 228,081 GT 2018
7 Harmony of the Seas Royal Caribbean 226,963 GT 2016
8 Oasis of the Seas Royal Caribbean 226,838 GT 2009
9 Allure of the Seas Royal Caribbean 225,282 GT 2010
10 MSC World America MSC Cruises 216,638 GT 2025

Source: Royal Caribbean and MSC Cruises published specifications, cross-checked against Wikipedia ship pages, retrieved 2026-09-17.

Gross tonnage isn't a weight

It's a common mix-up: gross tonnage sounds like it should measure how much a ship weighs, but it actually measures enclosed volume, calculated from a formula set out in the International Convention on Tonnage Measurement of Ships. A cruise ship's actual weight (its displacement) is a different, less-publicized number. GT is what shows up in "world's largest" headlines because it's the figure cruise lines report and maritime registries track consistently across every ship, which makes it the only fair way to compare a 2009 ship against one built in 2026.

Icon-class vs. Oasis-class: how they actually compare

Six of the top 10 are Oasis-class ships (Oasis, Allure, Harmony, Symphony, Wonder and Utopia of the Seas), the hull design Royal Caribbean introduced in 2009 and kept refining for 15 years. Oasis-class ships run about 361-362 meters (roughly 1,188 ft) long, with double-occupancy capacity that grew ship to ship as the design matured: Wonder of the Seas, for example, holds about 5,734 guests at double occupancy across 18 decks.

The newer Icon class (Icon, Star and Legend of the Seas) is Royal Caribbean's current flagship design: about 364.8 meters (1,197 ft) long, 20 decks, and roughly 5,610 guests at double occupancy. It's slightly longer than an Oasis-class ship but edges ahead mainly in GT and onboard features rather than sheer size, and the two classes are visibly in the same weight class next to almost anything else at sea.

MSC World America, the sole non-Royal-Caribbean ship in the top 10, is MSC's first true mega-ship at 216,638 GT and the largest LNG-powered cruise ship built to date, entering service in 2025.

Curious how each cruise line's own biggest ship stacks up, not just the overall top 10? See the cruise ship size comparison. Or check which of these ships calls at a specific port and when on the ports index, upcoming sailings, or the deck plans guide for how these ships lay out inside.

Frequently asked questions

What is the biggest cruise ship in the world?

Icon of the Seas and its sister ship Star of the Seas are tied for the largest cruise ships in the world at 248,663 gross tons each, both operated by Royal Caribbean. A third Icon-class ship, Legend of the Seas, joins them at the same tonnage in 2026.

What does "gross tonnage" mean for a cruise ship?

Gross tonnage (GT) is not a weight; it's a measure of a ship's total enclosed volume, calculated from a formula in an international convention. It's the standard figure cruise lines and maritime authorities use to compare ship size, which is why "biggest cruise ship" rankings are usually gross tonnage rankings, not length or passenger count.

How big is an Icon-class ship compared to an Oasis-class ship?

The two classes are close in scale but not identical. Icon-class ships (Icon, Star and Legend of the Seas) run about 364.8 meters (1,197 ft) long and carry roughly 5,610 guests at double occupancy. Oasis-class ships (Oasis through Utopia of the Seas) run slightly shorter, around 361-362 meters (about 1,188 ft), with double-occupancy capacity that varies by ship, roughly 5,400-5,700 guests.

Why does Royal Caribbean own most of the largest cruise ships?

Royal Caribbean has run the biggest hulls in the industry since the first Oasis-class ship launched in 2009, and it kept building on that design lineage through the newer Icon class. Eight of the current top 10 by gross tonnage are Royal Caribbean ships; MSC World America is the only non-Royal-Caribbean ship in the top 10, and the largest LNG-powered cruise ship built to date.

Is a bigger cruise ship a better cruise ship?

Not necessarily, it depends what you want. A larger ship usually means more dining venues, entertainment and cabin categories to choose from, along with slower embarkation and disembarkation and more crowded peak times at pools and shows. Smaller ships tend to dock closer to city centers and reach ports the biggest ships can't, so size is a trade-off, not a straightforward upgrade.