Why Royal Caribbean isn't going all in on massive cruise ships despite the wild success of its new Icon of the Seas

• Royal Caribbean International has unveiled a swath of giant cruise ships over the last few years.
• Its CEO said its new world's largest Icon of the Seas is its "best-selling product" ever.
• But the cruise line doesn't plan on going all in on mega-ships forever.

Earlier this year, guests at Royal Caribbean's Perfect Day at CocoCay private island were the first to revel at the historic sight of the two world's largest cruise ships, Icon of the Seas and Wonder of the Seas, docked side-by-side.

The vessels towered over their communal dock like skyscrapers, casting a dark shadow over their relatively tiny shared pier.

Together, they can accommodate up to 19,250 people.

At 1,198 feet long and 250,800 gross-tons, the Icon of the Seas is a sight to behold. When it launched in late January, the giant vessel upstaged its 10-foot shorter predecessor, Wonder of the Seas, as the world's biggest.

At the time, it was no surprise: It seems like every new Royal Caribbean ship dethrones another Royal Caribbean ship for this title.

But not for long.

The company's smaller ships, important for diverse trips, are aging.

The company is synonymous with its mega vessels. And they've been a mega-hit: Michael Bayley, president and CEO of Royal Caribbean International, has repeatedly called Icon of the Seas the "best-selling product" in the company's history.

Royal Caribbean is set to launch four more mega-ships by 2028, which will then represent about a third of its total fleet. So far, most of their scheduled sailings are in the Caribbean.

The other 21 smaller vessels tend to have more specialized itineraries, Patrick Scholes, an analyst at Truist Securities, told Business Insider.

Given their trimmer sizes, these vessels can operate more non-Caribbean sailings, which often reel in high fares and customer satisfaction for the company, Jay Schneider, chief product innovation officer at Royal Caribbean, told reporters in January. Think of the Mediterranean, Alaska, and South Pacific itineraries — the latter are especially important as the cruise line continues to ramp up business in Asia.

But these destination-flexible cruise liners are aging as Royal Caribbean continues to unveil their giant counterparts. The company's four oldest Vision-class ships, with a maximum 2,730-guest capacity, were launched between 1996 and 1998.

They're tiny and old compared to the two-month-old, 7,600-guest Icon of the Seas.

Looking ahead, Royal Caribbean plans to return to basics: smaller cruise ships.

Despite the cruise line's success with mega-vessels, Schneider said the Royal Caribbean is now considering a new class of ships that would start "smaller" — noting that he was "careful to say small, but less-than-large."

"The reality is, families want to go on vacations not just in the Western and Eastern Caribbean where a ship like Icon can get into," Schneider said. "They want to stay with our brand and journey to different destinations that require more versatility in ship size."

To curb pollution and overcrowding, desirable destinations like French Polynesia and Venice have limited visiting cruises, including size restrictions. But, as Schneider said, small-vessel-enabled specialized itineraries are also important to travelers.

Giant mass-market floating resorts also often attract first-time cruisers, enamored by their family-friendly waterparks and Broadway shows. But after a few good vacations at sea, these no-longer-new-to-cruise guests might start craving quieter ships or more bespoke itineraries.

"Alaska cruises tend not to be the first-time cruiser," Scholes told Business Insider. "I don't really see Icon of the Seas doing a Norwegian Fjord or Alaska trip."

Plus, "there's probably only so much demand for these giant ships," Scholes said.

Royal Caribbean has already succeeded in the first part: bringing in a swath of new cruisers with its mega-ships. Now, it has to retain them.