Cruise market leader Carnival Corp says its Carnival Cruise Line brand of 25 ships expects to continue catering to the mainstream market as the "world's most popular cruise line", carrying five million guests per year.

"With four new ships on order, we continue to build ships that cater to this market and don't have any plans on getting into the luxury or premium cruise segment," the company says.

It adds that many of its sister brands, including Seabourn Cruise Line and Cunard Line, offer packages in the luxury and premium markets.

Meanwhile, Carnival's rival, MSC Cruises, has big plans.

In June last year, MSC unveiled some details regarding its World Class series of at least two enormous LNG-powered cruiseships that are due to set to sail in 2022 and 2024.

Options are also on the table for two more of the same vessels for delivery in 2025 and 2026.

The ships — to be built by STX France — will have 2,760 cabins for 6,850 guests. And, if cruising now, they would carry more people than Royal Caribbean International's 6,780-passenger Harmony of the Seas, which is currently the world’s largest cruiseship.

MSC has been moving up the size scale with each successive order it has placed. But there are strong suggestions that the company is poised to order ships at the opposite end of the size spectrum.

According to reports circulating in European cruise circles, MSC is close to ordering four 700-passenger deluxe cruiseships at Fincantieri. In all likelihood, mass-market MSC will start a new upscale cruise brand to operate the ships.

MSC Cruises' Fincantieri-built cruiseship MSC Seaside Photo: MSC Cruises

The company is yet to shed any light on these suggested plans, although TradeWinds understands the order is imminent.

Norwegian Cruise Line and Royal Caribbean International — the other two that make up the "Big Four" cruise lines — declined to contribute details for this report.

But future orders placed by the companies and their associated brands indicate that, for the most part, they are basing their orderbook for the next five years on modified versions of their existing design platforms.

The exception is Royal Caribbean subsidiary Celebrity Cruises, which later this year will take delivery of the 129,500-gt, 2,918-passenger Celebrity Edge from STX France. This ship is being built to a completely new design and is the first of four of the class on order.