Luxury line Seabourn has confirmed it has exercised an option for a second new 604-passenger ship for delivery in 2018.

The 40,350-tonne vessel will be a sister ship to a new build announced earlier this year which is due for delivery in late 2016.

The new ships’ configuration will be based on Seabourn’s three Odyssey-class ships, with one additional deck and new expanded public areas.

Hospitality designer Adam Tihany will also design the second new ship in its entirety, including multiple dining venues; the spa; showrooms; casino and lounges; outdoor deck areas; and the Seabourn Square social hub of the ship.

Seabourn president Richard Meadows said: “There has been an incredible amount of excitement and interest since we announced the order for the first ship, and we’re very pleased that the demand for our brand has allowed us to add a second new ultra-luxury ship to our expanding fleet.

“These two new ships will offer the understated elegance we are known for, as well as new amenities, innovations and modern design features that embody the hallmarks of Seabourn.”

Giuseppe Bono, chief executive of Italian shipyard Fincantieri, where the vessels will be built, said: “When dealing with such important investments, exercising an option should never be taken for granted.

“We are very glad that Seabourn decided to ‘double’ its trust in us, especially considering that our partnership is very young and getting stronger quickly.

“I believe that this clearly demonstrates that new clients as well as old, such as Seabourn’s parent company Carnival Corporation, and the market as a whole, consider Fincantieri as the world leader in the cutting-edge cruise line sector including the ultra-luxury segment where our partner for this project operates.”