Building behemoth ships doesn't come cheap. 

The most-expensive cruise ship ever built, Royal Caribbean's Symphony of the Seas — which set sail for the first time last year — cost $1.35 billion to erect. 

Previously, Cunard's Queen Mary 2 held the distinction of being the priciest ship, costing £460 million at its launch in 2004. That ship weights 151,400 tons, is 1,132 feet long and can speed along at 35 miles per hour — making it also the fastest of any cruise ship in the world, an honor it still holds today.