Royal Caribbean's brand-new Harmony of the Seas, the world’s largest cruise ship, is 16 decks high, nearly as long as four football fields, and can carry 6,780 passengers and more than 2,000 crew. It feels like a floating city. And, like a city, the ship offers passengers lots and lots (and lots) of options from restaurants to entertainment to theme park-like attractions.

What are the benefits of being on such a huge ship?

Harmony offers plenty of choices, lots of places to explore, and nonstop action. If you want a drink, for example, ponder the options: There’s the Bionic Bar, where robots mix the martinis, the cozy wine bar, the outdoor tequila bar, the pub, and the Latin dance club (which serves lovely mojitos). And for something really unique, you can have Champagne in the 32-seat Rising Tide Bar, which literally rises like an open-air elevator, slowly ascending three decks. And that’s before you even consider your dinner options at 20 different restaurants, from a Johnny Rockets burger joint to 150 Central Park, an upscale restaurant with a menu created by chef Michael Schwarz of Michael's Genuine in Miami.

Then there’s the entertainment and attractions. Harmony is so big that it has been organized into seven neighborhoods. In Central Park, you’ll find paths that meander through more than 10,000 live plants and trees as well as posh shops (Bvlgari, Cartier, Hublot). Another neighborhood, the Boardwalk, holds a carousel, an amusement arcade, and the incredible AquaTheater, a 600-seat amphitheater with an 18-foot-deep pool where divers and aerial acrobats use 10-meter, Olympic-height diving boards to perform amazing shows. 

Elsewhere you’ll find an ice rink, a zip line, rock-climbing walls, surfing simulators, a full-sized basketball court, and a huge theater for Broadway shows. And then there’s Harmony's most-talked-about feature, The Ultimate Abyss, the tallest slide at sea: Riders enter one of two purple tubes and plummet down 10 decks of twists, turns, and sheer drops.

What’s the downside of a ship this size?

Being on a ship this big means you might have long hikes from one activity to the next. And at times it just feels like you’re in a shopping mall.

Moreover, glimpses of the ocean are rarer than you might think. Increased height and width creates more interior volume that allows for grand spaces, but it also creates hundreds of inward-facing staterooms that don't have sea views. Royal Caribbean makes these interesting by having them look out on Central Park or the Boardwalk, and some inside rooms have "virtual balconies" that broadcast real-time outside views on high-definition screens. 

Lastly, with so many people on board, lines can be long, and you’ll need to make reservations for headline entertainment (Broadway productions like "Grease," featured comedians, the ice shows, the diving spectaculars) and for specialty dining venues. (Eight of the ship's 20 dining venues carry service charges or are priced a la carte.)

What can passengers do about it?

Passengers can reserve seats for their preferred activities online before their trip or download the Royal iQ app on their mobile devices to connect, at no charge, to the ship's Intranet. Besides bookings, you can also use the app to see how much you're racking up at all those bars and restaurants. (A lot is included in the fare, but it's hard not to spend on a ship like this. You'll pay extra for the best burgers, coffee, steaks, and ice cream.)

And if you just feel like you need to get away from the crowds, there are some quiet spaces, like the card room and the partially shaded Solarium, which has cushioned sun beds.

The verdict?

If you thrive on big, bustling resorts, water parks, and action sports, you'll love it. 

Anne Kalosh doesn’t count the cruises she’s taken, although there have been hundreds—including five years as a shipboard newspaper editor, sailing the world. She loves the experiences sea travel offers. Her byline has appeared in many major publications, and she’s on top of the latest cruise developments as the long-time U.S. editor for and Seatrade Cruise Review.