At first glance, Royal Caribbean’s Navigator of the Seas may look like the same ship that launched 17 years ago. But when it steamed into PortMiami this month after a $115 million makeover, Navigator definitely had a new-generation attitude, complete with blow dry bar, triple-tiered outdoor bar and a pool deck worthy of a chic South Beach hotel.

With new vessels clocking in at a cool $1 billion-plus, refurbishing the dated-but-seaworthy makes good financial sense. But that’s where the similarities end.

Royal Caribbean’s Navigator will offer three- and four-day sailings that often attract vacationers who have never cruised before. For them, the refurbishments mean fresh options, said Colleen McDaniel, senior executive editor of Cruise Critic. “Traditionally, cruise lines have relegated older ships to those sailings. So cruisers who can’t get away for a full week were often sailing on ships that felt a bit older and lacked fun features. Nowadays, there are really great options for everyone.”

Such shorter cruises also appeal to getaway-seeking millennials. And that’s where Royal Caribbean is putting the focus with its $1 billion initiative to upgrade 10 older ships by 2022. Roughly $100 million of that went to last year’s upgrade of Mariner of the Seas, launched in 2003.

“Millennials are not coming back to us as much as we’d like, and new-to-cruise are coming to our oldest hardware. That’s the way we’re introducing them to our industry and then they’re not coming back either. How do you change that?” said Laura Hodges-Bethge, Royal Caribbean’s vice president of product development.

So Hodges-Bethge and her team set out to determine what it would take to get millennials and people who have never cruised before to consider cruising for their next weekend trip. Survey says: shallow pool deck, craft cocktail bar, sports bar, outdoor evening dining and more adrenaline-rush activities.

To test their new formula, they turned to the 4,000-passenger Navigator of the Seas.

When it was launched in 2002, Navigator was Royal Caribbean’s largest ship. It had two restaurants, a main dining room, two pools, and an indoor promenade — all designed to fight boredom and attract baby boomers.

But for today’s millennials, that’s old school.

Hodges-Bethge’s team used surveys to zero in on the precise features that today’s young guests appreciate most.

“We’re maniacal about guest research, down to we know what kind of steakhouse and why,” she said. “Back then [in 2002] it was the same thing, not on the level of steroids it’s on now with the level of granularity we go into it with, but pushing the envelope and giving guests things they’ve never seen before.”

On a recent Navigator sailing, passengers young and older lounged in the foot-deep ledge of the pool and flocked to the new blow dry bar for styling sessions.

Terry Miedema, a boomer from Michigan, first sailed on Navigator with his wife shortly after it was launched in 2002. He came back for a vacation with his wife and kids a few years later and returned to the ship for a third vacation post-renovation this March.

Today’s ships offer many more options, he said. “If you want it to be busy, it could be. If you want it to not be, it didn’t have to be. Between the mini-golf, slides, basketball court, there’s plenty to do if you want to do it.”

Eventually, cruise ships do retire after around 30 years. Instead of heading to Florida, retirement for a cruise ship may mean becoming a ferry.