The typical cruise ship can have 30 or more categories of rooms, most of which are unlovable spaces with tiny porthole windows or interior cabins with no windows at all. Cabins with large windows are most desirable, and ones with balconies are downright coveted. But the laws of supply and demand also means that those rooms are some of the most expensive, priced two or three times higher than the more plentiful interior cabins. Now Royal Caribbean, one of the world's largest cruise lines, has answered this challenge with high-tech wall-size video screens that display the real-time exterior view in high definition. The company's ship Navigator of the Seas, which is just completing a dry-dock upgrade, is the first to feature these virtual balconies in 81 of its staterooms. Framed by curtains and a safety railing to appear like a real balcony, the screen is matched with the sounds of the sea, piped through a sound system with a volume that can be adjusted.