Tui Cruises, the joint venture in Germany with Royal Caribbean Cruises, has ordered a ship for delivery in spring 2015.
The vessel will carry 2,500 passengers and be 99,300 gross tons in size.
It will be built at the Finnish shipyard STX, where a ship is already being built for Tui Cruises to enter service in 2014.
Construction work on the new vessel will start in 2013 and take two years
The ship will have many environmentally-friendly features, with a particular emphasis on the vessel’s energy efficiency, according to STX.
The shipyard’s chief operating officer Jari Anttila said: “We are extremely pleased that Tui Cruises confirmed the order of a sister ship for the magnificent Mein Schiff 3 cruise ship.
“We have reached this milestone of starting production of the first ship after a well-performed and intensive basic design phase. After this production starts, manning on this project will increase significantly during the coming months to reach the maximum level before summer next year.”
Tui Cruises chief executive Richard Vogel said: “After being just four years in the business and after successfully putting two ships on the market – Mein Schiff 1 and Mein Schiff 2 – we are proud to proceed with building our first new ship and that way continue the growth of our fleet.
“We have been extremely busy with the planning over the past two years, but now things are really starting to move.”