March 7 (Bloomberg) -- Royal Caribbean Cruises Ltd., the world's No. 2 cruise line, signed Aker Finnyards to build its third Freedom-class ship as it expands to meet rising demand.

The cost of the new ship is about $828 million, spokesman Michael Sheehan said. The vessel will contain 1,800 cabins that accommodate 3,600 guests double occupancy, Miami-based Royal Caribbean said in a statement today.

Freedom-class ships will be 15 percent larger than the company's Voyager vessels, which introduced activities such as rock-climbing walls and skating rinks. Royal Caribbean, which has 29 ships in service and two under construction, expects the new vessel to begin service in early 2008, two years after the Freedom class debuts in April 2006 with Freedom of the Seas.

Nineteen of the company's ships are in the Royal Caribbean International line and 10 are in the Celebrity line.

The third Freedom-class ship will expand Royal Caribbean's capacity in 2008 by 4.7 percent. Aker Finnyards is based in Turku, Finland.