World's 10 Largest Cruise Ships

Cruise ships have come a long way over the past several decades, expanding stateroom offerings, increasing the number of dining venues, enhancing onboard entertainment and testing the limits with attractions ranging from water slides to go-kart tracks. However, in doing so, cruise lines have had to build bigger ships. Here are the 10 largest as of April 2021 (based on gross tonnage).

The second ship in the Meraviglia-Plus class, MSC Cruises' MSC Virtuosa is tied for the ninth-largest in the world with a gross tonnage of 181,541 but measures just a few inches shorter than its sister ship, MSC Grandiosa. The ship was acquired earlier this year but has had its debut delayed due to the COVID-19 pandemic. Currently, the ship is slated to begin service in the U.K. as soon as next month.

MSC Virtuosa's sister ship, MSC Grandiosa was one of the first vessels to resume sailing in the wake of the pandemic, hosting more than 30,000 passengers between August 2020 and January 2021. MSC Cruises' Meraviglia Plus-class cruise ship boasts a gross tonnage of 181,541, a length of just over 1,087 feet and a maximum passenger capacity of 6,334.

Carnival Cruise Line's Mardi Gras is the newest ship among the world's largest. The ship's debut has been pushed back multiple times due to the pandemic but is currently on track to take to the seas this summer. The name Mardi Gras pays homage to Carnival's first ship, which checked in at just 27,000 tons compared to the newest one's 181,808 GT. The ship will feature the first roller coaster at sea as well as six distinct onboard zones, including Grand Center, French Quarter, Summer Landing, La Piazza, Lido and the Ultimate Playground.

The first of the new Excellence-class ships, AIDA Cruises' AIDAnova checks in at 183,858 GT and measures, 1,106 feet in length. The ship was delivered in late-2018, becoming the first cruise ship in the world able to operate completely on liquefied natural gas (LNG).

Like Carnival's Mardi Gras, P&O Cruises' Iona has had its debut delayed due to the COVID-19 pandemic. Nonetheless, with a gross tonnage of 184,089 and a length of a little more than 1,130 feet, Iona is the world's sixth-largest cruise ship. Perhaps the only thing more impressive than experiencing this 5,200-passenger vessel is watching how it came together.

Costa Cruises' Costa Smeralda boasts a gross tonnage of 185,010 and is the largest ship in the world to be fully powered by LNG, a low-impact fossil fuel that will play a key role in the industry's future. The ship debuted in 2019 and is scheduled to welcome a sister ship, Costa Toscana, later this year.

Allure of the Seas debuted as the world's largest passenger ship in 2010 but would be surpassed by one of her sister ships six years later. The 1,187-foot-long vessel has a gross tonnage of 225,282 with the ship's steel hull weighing approximately 54,000 tons. The award-winning ship is perhaps best known for its world-class onboard entertainment and unique attractions, including zipline rides and an interactive H20 Zone Water Park.

Royal Caribbean's Oasis of the Seas' arrival in 2009 marked the debut of the cruise line's Oasis class of ships, which are the largest passenger ships in the world. It's been more than a decade since the couple-friendly ship set a new capacity record for carrying more than 6,000 passengers. The ship was christened with seven godmothers-Gloria Estefan, Michelle Kwan, Dara Torres, Keshia Knight Pulliam, Shawn Johnson, Jane Seymour and Daisy Fuentes-to represent the seven different neighborhoods available to guests onboard.

Completed in 2016, Royal Caribbean's Harmony of the Seas boasts a gross tonnage of 226,963 and spans 1,188 feet-nearly a quarter of a mile-in length. The Oasis-class ship is named after the Harmony module on the International Space Station and is beloved for its water-based attractions, including the first water slides to debut on a Royal Caribbean ship and the tallest slide at sea in Ultimate Abyss.

Royal Caribbean's Symphony of the Seas currently boasts the distinction of being the largest cruise ship in the world by gross tonnage, checking in at an astonishing 228,081 GT. The 1,184-foot-long ship debuted in 2018, offering guests nearly two dozen restaurants and multiple pools and possessing enough room to accommodate a maximum of 6,680 passengers and a 2,200-person crew.