The Carnival Corp-owned brand has signed a deal with ship builders T.Mariotti and Damen to build the two 264-passenger vessels, which will be delivered in June 2021 and May 2022.

The 23,000-tonne ships will offer 132 veranda suites and will meet PC6 Polar Class standards allowing it to explore regions such as the Arctic and Antarctica.

Both ships will carry two submarines onboard as well as 24 Zodiac inflatable boats.

Richard Meadows, Seabourn’s president, said: “The combination of immersive experience, fine accommodations and sumptuous amenities offered by these new ships builds on the success of our current product and further demonstrates our leadership as innovators as we continue offering the finest ultra-luxury cruises available.”

Seabourn plans to announce design and service details for the ships later this year, with itineraries and booking information to be released in early 2019.

Current plans are for the first ship to sail in the Arctic in late summer 2021 followed by a full winter season in the Antarctic.