The vessels, to be named Bolette and Borealis, previously sailed as Amsterdam and Rotterdam, and can carry up to 1,380 and 1,404 guests.
They will become the two largest ships in Fred Olsen’s ocean fleet upon joining later this year.
Balmoral, Braemar, Boudicca and Black Watch are currently docked in Scotland awaiting returns to service.
In a statement, the line said Bolette and Borealis will boost capacity and “modernise” its fleet, ensuring the company “returns to the water in a stronger position”.
“I am delighted to be announcing this news today. We have chosen these vessels as they will fit seamlessly into our existing fleet of small ships, each carrying under 1,500 guests, bringing with them new and larger public areas whilst not compromising on our small ship experience,” said chairman Fred Olsen Jnr.
“The naming of the vessels is important to us. Bolette and Borealis are both names of ships we have had in years gone by.
“This increase in our capacity demonstrates our confidence in the future. With over 170 years of seafaring history, we have sailed through many difficult periods. With these new additions to the fleet, we will come out of this current situation stronger than ever, ready to deliver the award-winning itineraries that we are famous for.”
Managing director Peter Deer added: “This is an exciting chapter in the history of our company, and I know that our loyal and returning guests will be looking forward to exploring our new ships as soon as they can.
“Of course, we also hope to attract new guests to Fred Olsen Cruise Lines and we look forward to demonstrating the exceptional service that makes us the best UK cruise line for repeat business.”
