White ship VS Blue ship

Do you know why there is a cruise ship called white and one blue ship called?
Here's the story. Cruise ships on the face of the earth above the sea and sailing had been designed as the floating hotel, floating hotel alias. The facilities available are also very complete, starting from the casino, theater, swimming pool, fitness center & SPA, library yards to mini golf.
Part of the ship is usually divided into several levels, ie from the top is the sky deck, sports deck, Lido Deck, navigation deck, upper promenade, promenade, lower promenade, and the play deck. The main entrance or the entrance gate is usually on the main deck there. While steering the ship was in navigation deck.
The overall level of the visible and sea surface sticking. Meanwhile there are still several decks below sea level, where most of the crew lived, the A deck and B deck, and deck machinery for power generation.
For cruise ships under the flag of Holland America Lines (where I used to work) has a dominant color of navy blue, with white color combination on top. Meanwhile, other cruise ships have an average of pure white color. That is why, other than cruise ships is called ship white HAL. Famous names such as white ships: Carnival Cruise Line, Norwegian Cruise Line, Cunard Line, Royal Caribbean, Windstar Cruises, Seabourn Cruises, and Princess Cruises.