Carnival Corporation is the largest cruise ship holding company in the world. They own 98 different ships, and have about 13 on order (a few may already be afloat).  It owns Carnival Cruise Lines, Princess Cruises, Holland America Line, Costa, P&O Cruise, Cunard, Seabourn, AIDA and P&O Cruises Australia.  There are three other large holding companies but honestly, the best? Family-owned and operated, with ports of call on all seven continents, is the SilverSea. Ultra-luxury! Many Alaskan ports! Decades of cruising has shown me that none of these lines really care about what you do, as long as it's not murder or rape.  Just don't blow smoke in the captain's face and tip your cabin steward really well!