Cruise line executives are also driving the boom. Cruises have become more luxurious, stopping at more private islands and introducing celebrity chefs to their kitchens to draw customers.
In fact, the industry is expected to spend $6.8 billion in 2017 on new ships that can handle 30,000 more passengers, an investment that is expected to continue through 2018 and 2019.
"You don't spend that kind of dough unless you're feeling real confident about the future," Cramer said.
Take Carnival, which turned around under the leadership of CEO Arnold Donald after one of its ships capsized off the coast of Italy several years ago, when cruises were much less popular.
Carnival's purchasing power enabled Donald to cut costs by negotiating lower prices with suppliers. As cruises became more popular, Carnival also raised ticket prices because people were willing to pay up for experience and more on-deck amenities.
This March, Carnival shares hit a record high on strong earnings and revenue beats, and the company raised its full-year earnings forecast, bullish signs that cruises are picking up steam.
"And there's more cool stuff on the way — this fall, Carnival will be launching its Ocean Medallion program. That's an interactive platform that's meant to personalize your cruising experience. And, of course, they're still cutting costs while replacing old ships with more efficient new ones," Cramer added.
Roger Frizzell, senior vice president and chief communications officer at Carnival, confirmed to CNBC that the market for cruising is expanding.
"This is really a golden age for cruising," he said in an emailed statement. "Cruising is the best vacation value available as well as an amazing vacation experience. We believe our new OCEAN Medallion concept rolling out in November will help transform the guest experience to even higher levels."
Then there is Royal Caribbean, which Cramer dubbed the group's best performer. In 2014, the company began an initiative to double its earnings by 2017 and reach double-digit returns on invested capital, and the "Mad Money" host said it looks like the company will pull it off.
"In part, this strength is because of rising demand, but the company's also been very smart about cutting costs and providing customers with a superior product," he said.
Royal Caribbean's last earnings report beat on earnings and was in line with revenue estimates. Like Carnival, it announced that bookings were up, on-board revenues were growing, and embracing technology was keeping the company's on-deck experience fresh.
"The one piece of hair on this quarter? Well, it's kind of geopolitical," Cramer said. "China and South Korea are feuding over this new Korean missile defense system, so Royal Caribbean has had to remove South Korean tour destinations from its Chinese cruises."
While that hurt Royal Caribbean's numbers, its strength in the rest of the world balanced the loss, Cramer said.
Finally, Cramer turned to Norwegian Cruise, which came public in 2013. With a more modern fleet and strong routes that include an "effective monopoly" on Hawaiian cruises between the islands, the "Mad Money" host said the industry newbie has been showing its strength.
"Now, Norwegian reported last — we got their results three weeks ago — and in a way it seemed like they were penalized for the strength of both Royal Caribbean and Carnival," Cramer said.
Despite top and bottom line beats and strong guidance, Norwegian's stock slid after it reported, in part because of management's somewhat bearish commentary on the China-South Korea issue, and in part because investors were displeased with its large investments in marketing.
"But I think it's been punished enough," Cramer said. "The bookings were very, very strong worldwide on both volume and price, and marketing spending is just fine if it ends up pulling in more customers."
Andrea DeMarco, Norwegian Cruise Line's vice president of investor relations and corporate communications, said that she sees "tons of potential" in her company's growth prospects.
"A lot of our metrics are industry-leading even though we're the smallest of the three cruise operators," she told CNBC, adding that as Norwegian is trading at the best value of the three major cruise lines, now would be a good time for investors to jump in.
All in all, the cruise lines are not very expensive, with Carnival trading at 15 times next year's earnings, Royal Caribbean at 13 times, and Norwegian at 11 times 2018's expected numbers.
"Here's the bottom line: even though the cruise stocks have roared higher this year, I think the whole industry has more room to run," Cramer concluded. "The only problem is choosing among Carnival, Royal Caribbean, or Norwegian. I prefer Carnival — love that Arnold Donald — but really, I like 'em all and I bet they all go higher."
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