The booming expedition cruise sector is getting a little more crowded.

Seabourn, the luxury cruise line owned by Carnival Corp., announced plans on Monday to build two 264-passenger expedition ships arriving in 2021 and 2022. The ships will visit Antarctica, the Arctic, and other hard-to-reach global destinations.

They may have company. Expedition cruising is growing rapidly, with more than 25 ships on order, according to Cruise Industry News. New ships are coming from Ponant, Silversea, Hurtigruten, Lindblad — and now Seabourn.

“The way I see it is that the expedition industry is where the river cruise industry was five or 10 years ago — just being discovered, with a lot more potential to come,” said Ben Lyons, CEO of Expedition Voyage Consultants, which advises cruise lines on planning and operating expedition sailings.

And just last month, Royal Caribbean Cruises bought a majority stake in the luxury line Silversea Cruises for $1 billion, citing, in part, its expedition offerings.

“The ultra-luxury and expedition segments are growing at twice the rate that every other segment in the industry is growing,” Royal Caribbean Cruises CEO Richard Fain told Skift last month. “People want experiences. People are no longer just out there saying ‘What fancy new whiz-bang gadget can I get?’ … Not just what thing I can get but what memories.”

Carnival Corp., the world’s largest cruise company, does not include an expedition line in its portfolio. But Seabourn, which has five ships, has been playing in those waters already without specialized vessels.

The cruise operator started sailing to Antarctica in 2013, and offers a “Ventures by Seabourn” program that offers adventurous guided excursions in destinations including Alaska, Antarctica, Northern Europe, and the Amazon.

“We’ve been able to gauge our own succes and interest in the category,” said Richard Meadows, the cruise line’s president. “From that, clearly we believe that this was the right move for Seabourn.”

The ships will be purpose-built for expedition cruising by a partnership between shipbuilders T. Mariotti and Damen and will each include two submarines as well as kayaks and inflatable Zodiac exploration boats.

“That will allow us access into parts of the world based on the ice-strengthened hull that will be more extensive than what we can currently do today,” Meadows said.

The amenities will be classic Seabourn, with balcony suites, high-end dining, and other luxury touches.

“It really is the best in ultra-luxury expedition and cruising all tied together,” Meadows said.

Seabourn did not reveal the cost of the new ships, which will be 170 meters long and 23,000 gross tons.

Robin West, Seabourn’s vice president of expedition operations and planning, said in a statement that the line started developing “the concept for this next chapter of our expedition story” a year ago.

Evolution of Expedition

Expedition cruising has come a long way from its practical beginnings, which Lyons described as mostly using “hand-me-down former Russian vessels” that were functional but by no means luxurious.

“Passengers were not conventional cruisers,” Lyons wrote in an email from a cruise ship in Alaska, where he was on vacation. “They were die-hard enthusiasts who could tell you the difference between a tufted puffin or a horned puffin before even setting foot on the ship.”

He said that started to change about 10 years ago, as ships became more comfortable and conventional cruisers started coming around to the idea. Past expedition guests spread the word too, leading more people to try.

“The demand is potentially very high — but the supply is still very low,” Lyons said. “Even with all these new ships, we need to remember these are small ships; 200 passengers is considered a large ship in the expedition market. If you add up all the berths that are being built for the expedition industry now, even amidst this incredible boom, it still only equals approximately one of the largest Royal Caribbean ships being built.”

He pointed out that cruise lines want to get into the expedition scene because passengers pay top dollar for the experience — and may consider an expedition cruise even if they wouldn’t go on any other type of ship.

The Royal Caribbean-Silversea deal last month signaled that the world’s largest cruise operators were finally ready to seize the opportunity.

Carolyn Spencer Brown, Editor at Large at the industry news and review site Cruise Critic, said at the time that Royal Caribbean’s interest was an affirmation of the growth prospects for small-ship cruising.

“What they’re seeing is that small ships have an inordinate ability to convert travelers who haven’t cruised into cruise travelers,” Spencer Brown said in June. “It’s a very powerful niche of cruising right now.”

Photo Credit: A Seabourn ship is shown in Antarctica. The cruise line on Monday announced plans to build two new 264-passenger expedition ships. Seabourn