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Take an adventure to the ocean floor in a $2.9 million 3-person submarine, as part of this amazing cruise

People love cruises. By the end of 2017, 25.8 million people are expected to have taken one, according to the Cruise Lines International Association. But for those who board the Crystal Esprit — a 62-passenger expedition yacht that travels to the Adriatic and the West Indies — there's an extra special amenity: a once-in-a-lifetime ride on a high-tech personal submarine.

Crystal Cruises

This sleek submersible can dive up to 300 meters (about 984 feet), is air-conditioned, has a Bluetooth stereo system and carries two guests and a captain. And it comes with a hefty pricetag. According to Erik Hasselman, commercial director at the Netherlands-based U-Boat Worx, which made the sub, the cost of a new C-Explorer 3 like this starts at around €2.5 million ($2.95 million).

Being in the sub, which was originally built for scientific research, "is a magic experience," according to Hasselman.

"You simply submerge in a new world with the ease of stepping into your car and driving to the supermarket," he says. "The view from the inside is virtually unimpeded, so you can see 360-degrees around, which makes you feel like you're in an aquarium."

Crystal Cruises

Carolyn Spencer Brown, chief content strategist at Cruise Critic, sailed on the ship as a guest of Crystal and Brown tried out the submarine — which costs an additional $599 per person — during her trip.

"It was a fabulous way to journey to the depths of the sea without getting your hair wet," she says, explaining how the captain on the 20-minute trip played the soundtrack from "Finding Nemo." "We didn't find him, but loved the irony," she says.

"Everywhere you looked there were creatures to watch and none seemed bothered by the odd contraption sitting on the sea bed and three pairs of eyes staring out avidly."

Crystal Cruises

The Crystal Esprit itself is an all-suite yacht with butler service, food, drinks, excursions and special experiences, like lectures by astronaut brothers Scott and Mark Kelly, included in the rate. It launched in the Seychelles in 2015, and because it's an expedition ship, it can navigate smaller ports that larger vessels can't access.

Brown compares it to staying in a small boutique hotel. "There was nothing cruise-like about it," she says.

Crystal Cruise

Terri Rothe, a traveler from Nipomo, Calif., went to the Greek Isles on Crystal Esprit in June 2017. While she didn't try the submarine ("I'm a bit claustrophobic," she says), Rothe loved the ship's size ("It was easy to get on and off"), the food ("I've never even had food like that before") and the excursions, from cooking classes to a donkey ride on a Greek island with no cars.

For Rothe, the best part of being on the ship wasn't the high-tech water toys onboard. "I loved the simple things," she says. "Sitting outside was heaven."

Crystal Cruises

Still, in the cruise industry, ships are constantly trying to outdo each other with one innovation after the next — zip lines, ice-skating rinks, bowling alleys at sea.

This sub is a true game-changer, according to Anne Morgan Scully, president of McCabe World Travel. "People want something to talk about," Scully says. "And this is extraordinary."

John Stoll, vice president of land programs for Crystal, points out that the sub is a first for the cruise industry. "We pride ourselves on being pioneers in this space," he says.

For years, Crystal Cruises was one of the few lines that didn't compete on that level, relying instead on two ultra-luxury mid-sized ships to deliver high levels of service with butlers and all-inclusive amenities like free caviar. After the company was bought for $550 million in 2015 by China-based Genting Hong Kong, it embarked on a dizzying expansion plan that included a private 88-passenger jet called the Crystal Skye, river ships and more.

Cruise Critic's Brown predicts that cruise lines like Crystal will continue to step up offerings.

"We expect the addition of more really unusual toys going forward," she says. "Small ships are looking for ever more innovative options for travelers to experience the world, rather than just see it."

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