Nine cruise lines offer world cruises. These are their ships.
Crystal Cruises - an award-winning luxury line.
Cunard Line - the granddaddy of world cruises. 3 ships travel different routes.
Holland America Line - traditional luxury at a fair price. Mid-size ship.
Norwegian Cruise Line - casual, affordable ships.
Oceania Cruises - extra-long 180-day cruises. Upscale ship.
P & O Cruises - a UK cruise line. 2 ships make long voyages.
Princess Cruises - a relatively small ship. Mid-market brand.
Regent Seven Seas - all-suite, all-balcony ship design. Traditional luxury.
Seabourn Cruises - ultra-luxury smaller ship.
Silversea - an exclusive and luxurious smaller ship.
Celebrity Cruises and Royal Caribbean don't offer world cruises, but they do have some long cruises.